introduction: in clinical electron beams, most of bremsstrahlung radiation is produced by various linac head structures. this bremsstrahlung radiation dose is influenced by the geometry and construction of every component of the linac treatment head structures. thus, it can be expected that the amount of the contaminated photon dose due to bremsstrahlung radiation varies among different linacs,...

Background: Given the importance of scattered and low doses in secondary cancer caused by radiation treatment, the point dose of critical organs, which were not subjected to radiation treatment in breast cancer radiotherapy, was measured.Objective: The purpose of this study is to evaluate the peripheral dose in two techniques of breast cancer radiotherapy with two energies. Methods: Eight diff...

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...

background: monte carlo method (mc) has played an important role in design and optimization of medical linacs head and beam modeling. the purpose of this study was to compare photon beam features of two commercial linacs, varian 21ex and elekta sl-25 using mcnp4c mc code. materials and methods: the 6mv photon beams of varian 21ex and elekta sl-25 linacs were simulated based on manufacturers pro...

  Introduction: Several studies have discussed to the electron contamination caused by the air column between the head of linac and patient for photon beams. Since it is not possible to measure the electron contamination with practical dosimetry, the Monte Carlo technique is an appropriate and accurate choice to calculate particle flounce in radiation therapy. The purpose of t...

Background: Monte Carlo method (MC) has played an important role in design and optimization of medical linacs head and beam modeling. The purpose of this study was to compare photon beam features of two commercial linacs, Varian 21EX and Elekta SL-25 using MCNP4C MC code. Materials and Methods: The 6MV photon beams of Varian 21EX and Elekta Sl-25 linacs were simulated based on manufacturers pro...

background: the electron contamination may reduce or even diminish the skin sparing property of the megavoltage beam. the detailed characteristics of contaminant electrons are presented for different field sizes and cases. materials and methods: the monte carlo code, mcnpx, has been used to simulate 18 mv photon beam from a varian linac-2300 accelerator. all dose measurements were carried out u...

objective: using megavoltage photons generated by medical linear accelerator is a common modality for the treatment of malignant. the crucial problem for using photon beams >8mv is the photoneutron yields that increase the risk of secondary cancer that treated with high-energy photon beams. the contaminated neutrons produced in different components of the accelerator head and rely on many param...

Introduction: Photon contamination is a restriction on treatment with electron that increase dose to healthy tissue below the tumor. The aim of this study is to reduce the photon contamination using a magnet system. Materials and Methods: A mini-applicator equipped with two neodymium boron permanent magnets was designed which make it possible to adjust the d...