background: making use of the orthovoltage machines in radiotherapy, is one of the routine methods for the treatment of the superficial lesions. in this study, an important determinant of x-ray quality, the hvl (half value layer), has been evaluated. materials and methods: the hvls of a orthovoltage x-ray machine in 120 and 180 kvp are measured, using an empirical method, in which the hvls are ...

Background: Various variance reduction techniques such as forced detection (FD) have been implemented in Monte Carlo (MC) simulation of nuclear medicine in an effort to decrease the simulation time while keeping accuracy. However most of these techniques still result in very long MC simulation times for being implemented into routine use. Materials and Methods: Convolution-based force...

background: various variance reduction techniques such as forced detection (fd) have been implemented in monte carlo (mc) simulation of nuclear medicine in an effort to decrease the simulation time while keeping accuracy. however most of these techniques still result in very long mc simulation times for being implemented into routine use. materials and methods: convolution-based forced detectio...

one of the most important parameters used for determining the performance of tunnel boring machines (tbms) is their penetration rate. the parameters affecting the penetration rate can be divided in two categories. the first category is the controllable parameters such as the tbm technical characteristics, and type and geometry of the tunnel, and the second one is the uncontrollable parameters s...

As a popular simulation of photon propagation in turbid media, the main problem of Monte Carlo (MC) method is its cumbersome computation. In this work a table-based random sampling simulation (TBRS) is proposed. The key idea of TBRS is to simplify multisteps of scattering to a single-step process, through randomly table querying, thus greatly reducing the computing complexity of the conventiona...

background:  this study presents patient specific and organ dose estimation in computed tomography (ct) imaging of thorax directly from patient ct image using monte carlo simulation.  patient's ct image is considered as the patient specific phantom and the best representative of patient physical index in order to calculate specific organ dose. materials and methods: egsnrc /beamnrc monte c...

Background:  This study presents patient specific and organ dose estimation in computed tomography (CT) imaging of thorax directly from patient CT image using Monte Carlo simulation.  Patient's CT image is considered as the patient specific phantom and the best representative of patient physical index in order to calculate specific organ dose. Materials and Methods: EGSnrc /BEAMnr...

One of the most important parameters used for determining the performance of tunnel boring machines (TBMs) is their penetration rate. The parameters affecting the penetration rate can be divided in two categories. The first category is the controllable parameters such as the TBM technical characteristics, and type and geometry of the tunnel, and the second one is the uncontrollable parameters s...

We combine molecular dynamics (MD) and Monte Carlo (MC) simulations to study the properties of gas molecules confined between two hard walls of a microchannel or nanochannel. The coupling between MD and MC simulations is introduced by performing MD near the boundaries for accuracy and MC in the bulk because of the low computational cost. We characterize the influence of different densities and ...

We report on the RTGrid project, which investigates approaches for using high-performance computing infrastructures, such as the grid, in order to reduce the turnaround time of Monte Carlo (MC) simulation-based radiotherapy treatment planning. The main aim of this project is to render accurate dose calculations using MC simulations clinically feasible. To this end, we have successfully implemen...