Background: Monte Carlo (MC) modeling of a linear accelerator is a prerequisite for Monte Carlo dose calculations in external beam radiotherapy. In this study, a simple and efficient model was developed for Elekta SL-25 linear accelerator using MCNP4C Monte Carlo code Materials and methods: The head of Elekta SL-25 linac was simulated for 6 and 18 MV photon beams using MCNP4C MC code. Energ...

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...

The hydration of biomolecules is vitally important in molecular biology, so in this paper thesolvation energy and radial distribution function of DNA bases have been calculated by theMonte Carlo simulation.The geometries of isolated Adenine, Guanine, Cytosine, and Thyminehave been optimized using 6-31+G(d,p) basis function sets. These geometries then will be used inthe Monte Carlo calculation o...

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...

aquaporins are integral membrane proteins from a larger family of major intrinsic proteins that formpores in the membrane of biological cells. aquaporins form tetramers in the cell membrane with eachmonomer acting as a water channel.in this research, the aqp4 tetramer was modeled from its pdbstructure file, then, we have performed the intraction of aquaporin4 in different temperatures (298k,300...

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...

in this work, based on experimental observations and exact theoretical predictions, the kinetic scheme of raft polymerization is extended to a wider range of reactions such as irreversible intermediate radical terminations and reversible transfer reactions. the reactions which have been labeled as kinetic scheme are the more probable existing reactions as the theoretical point of view. the deta...

background: physical wedges are still widely used as beam modifiers in external beam radiotherapy. however the presence of them in the beam trace may cause beam hardening which may not be considered in many treatment planning systems. the aim of this study is to investigate the beam hardening effect generated by physical wedges via different beam quality indexes as photon spectrum, half value l...