X-ray fluorescence computed tomography (XFCT) is an experimental technique that can reconstruct the distribution of elements within the sample from the measurement of fluorescence stimulated from the sample[1]. The sample is irradiated with a x-ray beam, of which the energy is greater than the K-shell energy or L-shell energy of the interest elements. These x rays undergo photoelectric interact...

Progress in imaging and quantification of tissue perfusion using ultrasound (US) and microbubble contrast agents has been undermined by the lack of an effective automatic attenuation correction technique. In this article, an elementary model of the US attenuation processes for microbubble contrast enhanced imaging is developed. In the model, factors such as nonlinear bubble scattering, nonlinea...

Introduction: The role of radiotherapy as a part of cancer management increases every year around the world. Thus, Radiation protection in the design of radiotherapy rooms are of great importance.   Materials and Methods: In present study using Monte Carlo method, MCNPX code, fourteen types of developed high density concretes with densities ranging from 2.45 ...

Recent measurements of mass attenuation coefficients have identified the determination of the thickness of the absorbing specimen as the major limitation to the accuracy of the measurement. We present a technique for determining the mass attenuation coefficient with high accuracy. The technique uses the integral of the density along a column extending through the thickness of the absorber, whic...

Attenuation estimation methods for medical ultrasound are important because attenuation properties of soft tissue can be used to distinguish between benign and malignant tumors and to detect diffuse disease. The classical spectral shift method and the spectral difference method are the most commonly used methods for the estimation of the attenuation; however, they both have specific limitations...

introduction superficial x-ray therapy is one of the most important treatment methods in radiotherapy especially in the treatment of superficial skin lesions (up to 300 kvp). quality of the x-ray beam that can be expressed by half-value layer (hvl), are important indices for this type of treatment effective energy of photon and homogeneity coefficient (hc). materials and methods the hc of the s...

A novel variable optical attenuator device is proposed and some of the potential application is pointed out. It relies on a double acousto optic modulator set up and allows one to attain dynamic range as high as 60 dB. Such feature steams out of the well known modeling of acousto optic devices, mostly based on the coupled wave analysis. Furthermore, is shown that the proposed device may exhibit...