We have begun clinical trials of optical tomography of the neonatal brain. To validate this research, we have built and imaged an anatomically realistic, tissue-equivalent neonatal head phantom that is hollow, allowing contrasting objects to be placed inside it. Images were reconstructed by use of two finite-element meshes, one generated from a computed tomography image of the phantom and the o...

Introduction Accurate estimation of the absorbed dose in radiosensitive organs, located away from the target volume during radiotherapy, is one of the main reasons for the development of reference phantoms. The International Commission on Radiological Protection (ICRP) reference phantoms can provide a more realistic view of the human anatomy in comparison with the previously used mathematical p...

Objective: Different categories are available for estimating of radiation dose. Radioisotopes with the same energy and almost the same physical properties have similar effects. Monte Carlo technique is a computerized method based on mathematical simulation of physical processes. The main purpose of this study is to show that beta particles are not able to penetrate deep into the water. also dif...

Introduction:  Skin  sparing  is  one  of  the  most  desirable  characteristics  of  high  energy  photon  beams. However, the photons emerging from the target of linacs are contaminated by secondary  electrons  as  a  result  of  their  interactions  with  air,  collimators,  flattening  filter  and  any  other  objects in their path. This phenomenon tends to increase the skin dose received b...

This work presents a basic framework for constructing a 3D analytical MRI phantom in the Fourier domain. In the image domain the phantom is modeled after the work of Kak and Roberts on a 3D version of the famous Shepp-Logan head phantom. This phantom consists of several ellipsoids of different sizes, orientations, locations, and signal intensities (or gray levels). It will be shown that the k-s...

We have proposed a new frequency difference method using a weighted voltage difference (WFD-EIT) between two frequencies [1, 2]. Previous studies demonstrated its feasibility through numerical experiments and two-dimensional phantom experiments. In this study, we validate the WFD-EIT algorithm on a three-dimensional hemisphere phantom using a multi-frequency EIT system KHU Mark1. We built the h...

The aims of this study are to design, construct and evaluate the applicability of a head and neck Perspex phantom for dosimetric verification of intensity modulated radiation therapy (IMRT). Thermoluminescent dosimeters (TLDs) was used in this study. Consistency of the fabricated phantom readings was checked by multiple IMRT irradiations. The inter-fraction standard deviation among all TLDs’ me...

where E [V/m] is the amplitude of effective value of the electric field, σ [S/m] and ρ [kg/m] are the electric conductivity and the density of human tissue, respectively. In general, an approximation of a plane wave for the electromagnetic field has been applied to E in eq. (1) in order to represent the SAR characteristics in the internal parts of the head [1], [4]. For example, attenuation cha...

Electrical Impedance Tomography (EIT) has potential for imaging of the head to image cerebral edema and stroke, and to assist the EEG inverse problem. One key challenge is the low distinguishability of head EIT. In this paper, we develop a strategy to improve distinguishability by optimizing electrode configurations and stimulation and measurement patterns. In a hemispherical simulation phantom...

Radiofrequency (RF) field wave behavior and associated nonuniform image intensity at high magnetic field strengths are examined experimentally and numerically. The RF field produced by a 10-cm-diameter surface coil at 300 MHz is evaluated in a 16-cm-diameter spherical phantom with variable salinity, and in the human head. Temporal progression of the RF field indicates that the standing wave and...