introduction: esophageal cancer is one of the most frequently occurring cancers in iran and having a  high  incidence  rate  among  other  countries.  radiotherapy  is  one  of  the  three  methods  (surgery,  radiotherapy and chemotherapy) for radical or palliative treatment of esophageal cancer. in this method  of treatment, the organs such as heart and spinal cord are regarded as organs at r...

The present thesis is focused on the development and application of narrow scanned high energy photon beams for radiation therapy. The introduction of physically and biologically optimized intensity modulated radiation therapy (IMRT) requires a flexible and accurate dose delivery method to maximize the treatment outcome. Narrow scanned photon beams is a fast option for IMRT since it is not depe...

background: gold nanoparticles are emerging as promising agents for cancer therapy and are being investigated as drug carriers, photothermal agents, contrast agents and radiosensitisers. objective: the aim of this study is to understand characteristics of secondary electrons generated from interaction of gold nanoparticles gnps with x-rays as a function of nanoparticle size and beam energy and ...

The Photon Collider option of a Linear Collider (LC) is based on laser photon back-scattering on high energy electrons. The maximum photon energy is 205 GeV for a laser with λ = 1.06μm and an electron beam energy of 250 GeV. A high degree of polarisation with opposite helicities of the electron and the laser photon is crucial for obtaining a peaked spectrum of high energy polarised photons clos...

Abstract Purpose The physics design of the High Energy Photon Source (HEPS) was finished after many times iteration. Hereby, typical equilibrium electron beam parameters corresponding to proposed two baseline operation modes in HEPS are presented. Methods To compute beam, lattice parameters, RF and insertion devices (IDs) were determined first. Furthermore, it is more precise use full-current e...

ntroduction:  monte  carlo  simulation  is  the  most  accurate  method  of  simulating  radiation  transport  and  predicting doses at different points of interest in radiotherapy. a great advantage of the monte carlo method  compared  to  the  deterministic  methods  is  the  ability  to  deal  accurately  with  any  complex  geometry.  its  disadvantage is the extremely long computing time r...

Objective: In this study, we aimed to validate the accuracy of computed tomography-based attenuation correction (CTAC) using the bilinear scaling method.Methods: The measured attenuation coefficient (μm) was compared to a theoretical attenuation coefficient (μt ) using four different CT scanners and an RMI 467 phantom. The effective energy of the CT beam X-rays was calculated, using the aluminu...

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: Today, radiotherapy combined with surgery in the treatment of parotid tumors widely are used specially for high grade parotid tumors. One of concern and challenge issue of radiotherapy is that the treatment of these tumors with irregular surface due to the presence of external ear and region of different physical electron density (air cavities, dense bone, soft t...