introduction lead-based shields are the most widely used attenuators in x-ray and gamma ray fields. the heavy weight, toxicity and corrosion of lead have led researchers towards the development of non-lead shields. materials and methods the purpose of this study was to design multi-layered shields for protection against x-rays and gamma rays in diagnostic radiology and nuclear medicine. in this...

introduction: among different kinds of oral cavity cancers, the frequency of tongue cancer occurrence is more significant. brachytherapy is the most common method to cure tongue cancers. long sources are used in different techniques of tongue brachytherapy. the objective of this study is to asses the dose distribution around long sources, comparing different radioisotopes as brachytherapy sourc...

in the present study, the kinetics of biodiesel production through transesterification of brassica carinata oil with methanol in the presence of potassium hydroxide is investigated by kinetic monte carlo simulation. the obtained results from simulation agree qualitatively with the existing experimental data. the kinetics data for each step of suggested mechanism are confirmed by simulation. by ...

background: most preclinical studies are carried out on mice. for internal dose  assessment of a mouse, specific absorbed fraction (saf) values play an important role.  in most studies, saf values are estimated using older standard human organ compositions  and values for limited source target pairs. objective: saf values for monoenergetic photons of energies 15, 50, 100, 500,  1000 and 4000 ke...

aims: the aim of the present work is (1) to evaluate dose calculation accuracy of two commonly used algorithms for 15 mv small photon fields in a medium encompassing heterogeneity and (2) compare these results with measured results obtained using gafchromic film ebt2. materials and methods: authors employed kailwood (pinus wallichiana) to mimic lung. briefly, seven kailwood plates, each measuri...

in this paper we focus on a continuously deteriorating two units series equipment which its failure can not be measured by cost criterion. for these types of systems avoiding failure during the actual operation of the system is extremely important. in this paper we determine inspection periods and maintenance policy in such a way that failure probability is limited to a pre-specified value and ...

background: high density concrete is extensively used for efficient radiation attenuation in radiotherapy rooms and nuclear reactors. over the past eight years, some efficient galena-based concrete samples for shielding x or gamma rays was produced. the goal of this study was to produce a novel high density concrete against neutron and photon radiations using tourmaline and galena. materials an...

background: the characteristics of secondary neutrons in a high energy radiation therapy room were studied using the mcnpx monte carlo (mc) code. materials and methods: two mc models including a model with full description of head components and a simplified model used in previous studies were implemented for mc simulations. results: results showed 4-53% difference between full and with the sim...

deregulation policy has caused some changes in the concepts of power systems reliability assessment and enhancement. in this paper, generation reliability is considered, and a method for its assessment using intelligent systems is proposed. also, because of power market and generators’ forced outages stochastic behavior, monte carlo simulation is used for reliability evaluation. generation reli...

wind power generation is variable and uncertain. in the power systems with high penetration of wind power, determination of equivalent operating reserve is the main concern of systems operator. in this paper, a model is proposed to determine operating reserves in simultaneous market clearing of energy and reserve by stochastic programming based on scenarios generated via monte carlo simulation ...