Background: Neutron contamination is produced in electron beams of linac when tooth or dental materials are located in the path of beam. Objective: This study aims to determine the neutron dose contamination from different dental restoration materials in electron mode of a linac. Material and Methods: In this experimental study, the neutron dose contamination was calculated in the p...

The analytical anisotropic algorithm (AAA) was implemented in the Eclipse (Varian Medical Systems) treatment planning system to replace the single pencil beam (SPB) algorithm for the calculation of dose distributions for photon beams. AAA was developed to improve the dose calculation accuracy, especially in heterogeneous media. The total dose deposition is calculated as the superposition of the...

A simple direct acceleration model is proposed, taking into account the stochastic phase disturbance of the coherent driving laser fields. A relativistic single particle simulation shows that plasma electrons are efficiently accelerated far above the ponderomotive energy. The energy and momentum distributions of the accelerated electrons are derived to examine the effects of the self-generated ...

Background: Small photon fields are increasingly used in modern radiotherapy especially in intensity modulated radiation therapy (IMRT) and stereotactic radiosurgery (SRS) treatments. Accurate beam profile and central axis depth doses measurements of such beams are complicated due to the electron disequilibrium. Hence the EBT2 (external beam therapy) Gafchromic film was used for dosimetry of sm...

Introduction: Megavoltage X-ray beams are used to treat cervix cancer due to their skin-sparing effect. Preferably, the radiation surface doses should be negligible; however, it increases due to electron contamination produced by various field parameters. Therefore, it is essential to provide proper knowledge about the effect of different field parameters on radiation doses. This study sought t...

background: the presence of a wedge filter in the beam trajectory can modify the beam quality and cause some changes in the dosimetry parameters which are usually difficult to be measured directly and accurately. material and methods: in this study the mcnp-4c monte carlo code was used to simulate the 9 mv photon beam generated by a linear accelerator. upon getting a good agreement between the ...

Introduction: During intensity modulated radiation therapy (IMRT) technique, theoretically, presence of flattening filter (FF) across the beamline of clinical linear accelerator (linac) is not essential to obtain uniform lateral profiles due to intensity modulation of photon beams by multileaf collimators (MLCs). The aim of this study was to investigate the dosimetrical propert...

Background: The purpose of this work is to discover and analyze errors and incidents in some radiotherapy centers, and to introduce methods that could reduce their occurrences, especially those which had happened due to the use of improper and inadequate equipment. This work is a first step toward clarifying the role of education in a risk-conscious culture, and changing the attitude of radioth...

background: the purpose of this study was to investigate the application of the monte carlo technique to calculate and analysis of dosimetric parameters for electron beams used in radiotherapy. this technique is based on statistical method and has a powerful role in different radiotherapy aspects. materials and methods: the simulated medical linear accelerator was the varian clinac 2100c. the e...