objective: in this study, we aimed to validate the accuracy of computed tomography-based attenuation correction (ctac) using the bilinear scaling method.methods: the measured attenuation coefficient (μm) was compared to a theoretical attenuation coefficient (μt ) using four different ct scanners and an rmi 467 phantom. the effective energy of the ct beam x-rays was calculated, using the aluminu...

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 ...

background: in megavoltage radiotherapy rooms, ordinary concrete is usually used due to its low construction costs, although higher density concrete are sometimes used, as well. the use of high-density concrete decreases the required thickness of the concrete barrier hence, its disadvantage is its high cost. in a nuclear reactor, neutron radiation is the most difficult to shield. a method for p...

  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 designed service life of Hong Kong-Zhuhai-Macao Bridge is 120 years. Concrete quality control for the submerged tunnel of the project is an important work to assure the designed service life. This article is to present an advanced concrete performance prediction method based on water–binder ratio (w/b) monitoring, which is used to serve for concrete quality control. During experiments in th...

background: biological shielding of nuclear reactors has always been a great concern and decreasing the complexity and expense of these installations is of great interest. in this study, we used datolite and galena (daga) minerals for production of a high performance heavy concrete. materials and methods: datolite and galena minerals which can be found in many parts of iran were used in the con...

background: attenuation coefficient (μ) plays an important role in calculations of treatment planning systems, as well as determination of dose distributions in external beam therapy, dosimetry, protection, phantom materials and industry. so, its exact measurement or calculation is very important. the aim of this study was to evaluate the μ in different points in the water phantom analytically ...

BACKGROUND In this study, a method for linear attenuation coefficient calculation was introduced. METHODS Linear attenuation coefficient was calculated with a new method that base on the physics of interaction of photon with matter, mathematical calculation and x-ray spectrum consideration. The calculation was done for Cerrobend as a common radiotherapy modifier and Mercury. RESULTS The val...

It is widely accepted that, on ensemble average, the transmission T of guided modes decays exponentially with the waveguide length L due to small imperfections, leading to the important figure of merit defined as the attenuation-rate coefficient α=-⟨ln(T)⟩/L. In this Letter, we evidence that the exponential-damping law is not valid in general for periodic monomode waveguides, especially as the ...

Background: In megavoltage radiotherapy rooms, ordinary concrete is usually used due to its low construction costs, although higher density concrete are sometimes used, as well. The use of high-density concrete decreases the required thickness of the concrete barrier hence, its disadvantage is its high cost. In a nuclear reactor, neutron radiation is the most difficult to shield. A method for p...