introduction: in this paper, by complete definition of human eye containing the various parts and their materials, the difference between this model and a homogeneous water phantom are compared for two ophthalmic plaques using 125i and 103pd. material and methods: the simulation of the two phantoms were performed in the mcnp-4c code and by using the geometry of a three-dimensional eye, differen...

introduction in order to treat uveal melanoma , first, radioactive seeds are laid on a silicone- made substance which is called silastic after that they are inserted in the plaque, and finally, this plaque containing silicone-made substance is stitched to the sclera surface. the dose gradient within the tumor and healthy tissues can be varied due to changing the silastic thickness between scler...

background: in radiation therapy, water is the phantom material of choice, both for reference and for relative dosimetry measurements. solid phantoms, however, are more useful for routine measurements because they tend to be more robust and easier to set up than water phantoms. materials and methods: fluka input data cards have been arranged in sequential order. a simple cylindrical geometry wi...

some of the most destructive accidents of 1980s and 90s which occurred in process industries were domino accidents. although domino accidents are among the most destructive industrial accidents, there are not much pioneering works done on quantification of them. the analytical formulation of the domino accidents is usually complex and need a deep knowledge of probability rules. even if the case...

in this paper, we focus on a continuously deteriorating critical equipment which its failure cannot be measured by cost criterion. for these types of systems like military systems, nuclear systems, etc it is extremely important to avoid failure during the actual operation of the system. in this paper we propose an approach which constrains failure probability to a pre-specified value. this valu...

b a c k g r o u n d & aim: the aim of the current study was to investigate the advantages of bayesian method in comparison to traditional methods to detect best antioxidant in freezing of human male gametes. methods  &  materials:   semen  samples  were  obtained  from  40  men  whose  sperm  had  normal criteria. a part of each sample was separated without antioxidant  as fresh and the remaini...

background: high-velocity carbon ion beams represent the most advanced tool for radiotherapy of deep-seated tumors. currently, the superiority of carbon ion therapy is more prominent on lung cancer or hepatomas. materials and methods: the data for lateral straggling and projected range of monoenergetic 290 mev/u (3.48 gev) carbon ions in muscle tissue were obtained from the stopping and range o...

atom transfer radical polymerization (atrp) of styrene was carried out at 105°c and a monte carlo simulation was employed to model the system. the variations of monomer conversion, the initiator concentration, average molecular weight, and molecular weight distribution were evaluated as the reaction proceeded. according to the results obtained, for similar reaction time, monomer conversion is h...

this study aims to undertake a statistical study to evaluate the accuracy of nine models that have been previously proposed for estimating the ultimate resistance of plate girders subjected to patch loading. for each model, mean errors and standard errors, as well as the probability of underestimating or overestimating patch load resistance, are estimated and the resultant values are compared o...

background: the presence of a wedge filter in the beam trajectory can modify the beam quality and cause some changes in the dosimetry parameters which are usually difficult to be measured directly and accurately. material and methods: in this study the mcnp-4c monte carlo code was used to simulate the 9 mv photon beam generated by a linear accelerator. upon getting a good agreement between the ...