BACKGROUND In radiotherapy treatment, the calculation of radiation dose distribution in target volume lead to an optimum set of planning parameters. This worked has been aimed to compare two photon beam dose calculation algorithms in the Oncentra Treatment Planning system for Varian Linear Accelerator, to assure the quality of treatment planning. METHODS Monitor Units to be delivered on norma...

Background: Recently, different investigators have studied the possibility of radiation therapy in restenosis prevention and have shown promising results. In this study a unique radioactive source for intra vascular brachytherapy (IVBT) was investigated. The two-dimensional dose distribution in water for a 32P IVBT stent has been calculated. The pure beta emitter source 32P has been co...

Background: In treating patients with radiation, the degree of accuracy for the delivery of tumor dose is recommended to be within ± 5% by ICRU in report 24. The experimental studies have shown that the presence of low-density inhomogeneity in areas such as the lung can lead to a greater than 30% change in the water dose data. Therefore, inhomogeneity corrections should be used in treatment pla...

Introduction: Gamma Knife is an instrument specially designed for treating brain disorders. In Gamma Knife, there are 201 narrow beams of cobalt-60 sources that intersect at an isocenter point to treat brain tumors. The tumor is placed at the isocenter and is treated by the emitted gamma rays. Therefore, there is a high dose at this point and a low dose is delivered to the normal tissue surroun...

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. energy sp...

introduction: gamma knife is an instrument specially designed for treating brain disorders. in gamma knife, there are 201 narrow beams of cobalt-60 sources that intersect at an isocenter point to treat brain tumors. the tumor is placed at the isocenter and is treated by the emitted gamma rays. therefore, there is a high dose at this point and a low dose is delivered to the normal tissue surroun...

Background: This study aims to calculate the air-kerma strength (SK), the dose rate constant (∧) and the dose rate profiles of a Gammamed 12i Ir-192 source by using the Monte Carlo technique and to compare the dose rate values with those calculated by the Abacus HDR treatment planning system (TPS). Materials and Methods: Air-kerma strength (in units of U; 1 U= μGy m2 h-1) and the dose ra...

BACKGROUND Photon beam is most widely being used for radiation therapy. Biological effect of radiation is concerned with the evaluation of energy absorbed in the tissues. It was aimed to analyse the depth dose characteristics of x-ray beams of diverse energies to enhance the quality of radiotherapy treatment planning. METHODS Depth dose characteristics of different energy photon beams in wate...

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...