in present pet/ct scanners, pet attenuation correction is performed by relying on the information given by ct scan. in the ct-based attenuation correction methods, dual-energy technique (dect) is the most accurate approach, which has been limited due to the increasing patient dose. in this feasibility study, we have introduced a new method that can implement dual-energy technique with only a si...

Subgenomic (sg) mRNAs are small viral messages that are synthesized by polycistronic positive-strand RNA viruses to allow for the translation of certain viral proteins. Tombusviruses synthesize two such sg mRNAs via a premature termination mechanism. This transcriptional process involves the viral RNA-dependent RNA polymerase terminating minus-strand RNA synthesis prematurely at internal RNA si...

The campaign to collect rain attenuation data on terrestrial links had commenced in Malaysian tropical climates for almost two decades. The terrestrial data so far collected have been greatly utilized to derive useful statistics for various microwave applications, such as frequency scaling, rain rate conversion factor, 1-min rain rate contour maps, wet antenna losses, and fade slope duration an...

Background: Lead glass has a wide variety of applications in radiation protection. This study aims to investigate some characteristics of lead glass such as the γ-ray energy-dependent mass and linear attenuation coefficients, the half-value layer thickness, and the absorbed dose distribution for specific energy. Materials and Methods: The attenuation parameters of different lead glass types aga...

background: photon attenuation as an inevitable physical phenomenon influences on the diagnostic information of spect images and results to errors in accuracy of quantitative measurements. this can be corrected via different physical or mathematical approaches. as the correction equation in mathematical approaches is nonlinear, in this study a new method of linearization called ‘piece wise line...

  Introduction:  The use of radioactive iodine (131I) has become an important adjunct to the treatment of thyroid cancer and hyperthyroidism. Salivary gland has the ability to concentrate radioactive iodine under normal circumstances. Salivary gland dysfunction and dry mouth are the common side effectsof high-dose radioiodine therapy. The purposeof this stu...

The characterization of the incident photon beam is usually divided into its dependence on collimator setting (head-scatter factor) and off-axis position (primary off-axis ratio). These parameters are normally measured "in air" with a build-up cap thick enough to generate full dose build-up at the depth of dose maximum. In order to prevent any influence from contaminating electrons, it has been...

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...

The sound attenuation of a silencer consisting lamella network made with melamine foam inserted in rectangular duct is investigated numerically and experimentally. arrangement designed so that skeleton bending elastic resonances appear at low frequency. In addition to this phenomenon, viscothermal losses the porous material ensure broadband attenuation. provides natural sub-wavelength resonator...