one of known methods for measuring, forecasting and managing risk is value at risk, which recently has been used by financial institutions extensively. value at risk (var) is a method for recognizing and evaluating risk and uses standard statistical techniques that have daily using in other contexts. this research is seeking a career for managing investment risk in stock exchange and selection ...

Purpose: In the last years, some studies investigated dosimetric benefits of a free flattening filter for the photon mode in the radiotherapy field. This study aims to provide a theoretical study published and analysis of basic dosimetric properties for a Saturne 43 Linac head to implement free flattening filter beams clinically. Material and Methods: Thi...

background: the monte carlo method is the most accurate method for simulation of radiation therapy equipment. the linear accelerators are currently the most widely used machines in radiation therapy centers. methods: in this work, a monte carlo modelling of the siemens oncor linear accelerator in 6 mv and 18 mv beams was performed. the results of simulation were validated by measurements in wat...

We show how nowadays it is possible to achieve the goal of accuracy and fast computation response in radiotherapic dosimetry using Monte Carlo methods, together with a distributed computing model. Monte Carlo methods have never been used in clinical practice because, even if they are more accurate than available commercial software, the calculation time needed to accumulate sufficient statistic...

Background: The dosimetric parameters required in lung cancer radiation therapy are taken from a homogeneous water phantom; however, during treatment, the expected results are being affected because of its inhomogeneity. Therefore, it becomes necessary to quantify these deviations.Objective: The present study has been undertaken to find out inter- and intra- lung density variations and its dosi...

A general-purpose, object oriented software system has been developed for the simulation and dosimetric analysis of brachytherapy applications. The flexible object-oriented design makes this system very versatile, offering the possibility to configure it for different types of brachytherapy techniques (such as I-125 or Ir-192, for instance). The dosimetric system is based on the Geant4 Simulati...

background: the purpose of this project was to derive the brachytherapy dosimetric functions described by american association of physicists in medicine (aapm) tg-43 u1 based on high dose rate 192i sources. materials and methods: the method utilized included both simulation of the designed polymethyl methacrylate (pmma) phantom using the monte carlo of mcnp4c and benchmarking of the simulation ...

The recent popularity of permanent implants for treatment of prostate cancer has created a large demand for low energy seed sources. Vendors have introduced new source designs to meet this demand. The AAPM has recommended that all low energy interstitial brachytherapy seed sources be subjected to independent dosimetric evaluations, preferably using experimental measurements as well as Monte Car...