background: an effective method for management of large and bulky malignant tumors. this treatment modality is also known as specially fractionated radiation therapy (sfrt). in this treatment technique a grid block converted the open radiation field into a series of pencil beams. dosimetric characteristics of an external beam grid radiation field have been investigated using experimental and mo...

in this paper, we calculate electron and hole impactionization coefficients in in0.52al0.48as using a monte carlo modelwhich has two valleys and two bands for electrons and holesrespectively. also, we calculate multiplication factor for electronand hole initiated multiplication regimes and breakdown voltagein in0.52al0.48as pin avalanche photodiodes. to validate themodel, we compare our simulat...

ntroduction:  monte  carlo  simulation  is  the  most  accurate  method  of  simulating  radiation  transport  and  predicting doses at different points of interest in radiotherapy. a great advantage of the monte carlo method  compared  to  the  deterministic  methods  is  the  ability  to  deal  accurately  with  any  complex  geometry.  its  disadvantage is the extremely long computing time r...

background: megavoltage beams used in radiotherapy are contaminated with secondary electrons. different parts of linac head and air above patient act as a source of this contamination. this contamination can increase damage to skin and subcutaneous tissue during radiotherapy.  monte carlo simulation is an accurate method for dose calculation in medical dosimetry and has an important role in opt...

kinetic monte carlo simulation was applied to investigation of kinetics and mechanism of oxalic acid degradation by direct and heterogeneous catalytic ozonation. la-containing perovskites including lafeo3, lanio3, lacoo3 and lamno3 was studied as catalyst for oxalic acid ozonation. the reaction kinetic mechanisms of each abovementioned catalytic systems has been achieved. the rate constants val...

Background: An effective method for management of large and bulky malignant tumors. This treatment modality is also known as Specially Fractionated Radiation Therapy (SFRT). In this treatment technique a grid block converted the open radiation field into a series of pencil beams. Dosimetric characteristics of an external beam grid radiation field have been investigated using experimental and Mo...

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...

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...