Currently the Gamma Knife system is accompanied with a treatment planning system, Leksell GammaPlan (LGP) which is a standard, computer-based treatment planning system for Gamma Knife radiosurgery. In LGP, the dose calculation algorithm does not consider the scatter dose contributions and the inhomogeneity effect due to the skull and air cavities. To improve the dose calculation accuracy, Monte...

background: one of the main problems of dedicated iort accelerators is to determine dosimetric characteristics of the electron beams. monte carlo simulation of iort accelerator head and produced beam will be useful to improve the accuracy of beam dosimetry. materials and methods: liac accelerator head was modeled using the beamnrcmonte carlo simulation system. phase-space files were generated a...

A Classical Trajectory Monte Carlo (CTMC) simulation has been made of processes of charge exchange and ionization between an hydrogen atom and fully stripped ions embedded in very strong static electric fields (O(10 V/m)), which are thought to exist in cosmic and laser–produced plasmas. Calculations show that the presence of the field affects absolute values of the cross sections, enhancing ion...

In this paper, we present an ensemble Monte Carlo model to calculate the time response for GaAs MSM photodetectors. Our model includes two valleys and two bands for electrons and holes respectively. We simulate optical pulse absorption and trajectory of carriers to calculate electron and hole currents. Also, we calculate the effect of different voltages and optical pulses on photocurrent. To va...

A kinematically complete experiment for simultaneous ionization of a projectile and target has been performed for 3.6 MeV/u C2+ on He collisions measuring the final vector momenta of the He1+ recoil ion and of two electrons (projectile, target) in coincidence with the emerging C3+ projectile. The feasibility of an event-by-event separation of the various reaction channels, among them the ioniza...

One of the most important methods employed to measure the market risk is value at risk calculation method. In this study, the value at risk of banks listed on the Tehran Stock Exchange and Over-the-counter (OTC) are calculated using parametric model, Monte Carlo simulation, historical simulation and Two-Sided Power (TSP) Distribution. The sample includes all listed banks in Iran. The results sh...

Introduction After the publication of Task Group number 43 dose calculation formalism by the American Association of Physicists in Medicine (AAPM), this method has been known as the most common dose calculation method in brachytherapy treatment planning. In this formalism, the water phantom is introduced as the reference dosimetry phantom, while the attenuation coefficient of the sources in the...

background: stereotactic radiosurgery is an important clinical tool for the treatment of small lesions in the brain, including benign conditions, malignant and localized metastatic tumors. a dosimetry study was performed for elekta ‘synergy s ’ as a dedicated stereotactic radiosurgery unit, capable of generating circular radiation fields with diameters of 1-5 cm at isocentre using the beam/egs4...