background: monte carlo and experimental relative dose determination in a water phantom, due to a high dose rate (hdr) 192ir source is presented for real energy spectrum and monochromatic at 356 kev. materials and methods: the dose distribution has been calculated around the 192ir located in the center of 30 cm ×30 cm ×30 cm water phantom using mcnp4c code by monte carlo method. relative dose v...

introduction: secondary radiation such as photoelectrons, auger electrons and characteristic radiations cause a local boost in dose for a tumor when irradiated with an external x-ray beam after being loaded with elements capable of activating the tumor, e.g.; i and gd. materials and methods:  in this investigation, the mcnpx code was used for simulation and calculation of dose enhancement facto...

Previous investigators of EPID dosimetric properties have ascribed the backscatter, that contaminates dosimetric EPID images, to its supporting arm. Accordingly, Monte-Carlo (MC) EPID models have approximated the backscatter signal from the layers under the detector and the robotic support arm using either uniform or non-uniform solid water slabs, or through convolutions with back-scatter kerne...

Because of the adverse effects of ionizing radiation on fetuses, prior to radiotherapy of pregnant patients, fetal dose should be estimated. Fetal dose has been studied by several authors in different depths in phantoms with various abdomen thicknesses (ATs). In this study, the effect of maternal AT and depth in fetal dosimetry was investigated, using peripheral dose (PD) distribution evaluatio...

Electron beam radiation therapy is used extensively for treating head and neck cancers to avoid the irradiation of the spinal cord. It is also used for treating chest wall malignancies to limit the irradiated volume of lungs. Calculating the dose distribution from an electron field is quite complicated because of the multiple scattering, especially in the presence of internal heterogeneities [1...

*Corresponding author: Dr. Asghar Mesbahi, Medical physics department, Medical school, Tabriz university of Medical Sciences, Tabriz, Iran. Fax: +98 411 3364660 E-mail: [email protected] Background: The characteristics of secondary neutrons in a high energy radiation therapy room were studied using the MCNPX Monte Carlo (MC) code. Materials and Methods: Two MC models including a model with...

Stopping power ratios sw,air for electron beams produced by the NOVAC7® IORT accelerator were calculated at different depths in water by the SPRRZnrc Monte Carlo code. As input for the SPRRZnrc code a phase-space data file obtained for any beam by the BEAMnrc code was used. The calculated stopping power ratios were compared with those recommended by the IAEA dosimetry protocols TRS-381 and TRS-...

With recent development of new methods such as intensity modulated radiation therapy (IMRT) for radiation delivery, dose fields can, in principle, be generated in near-conformal three-dimensional (3-D) distributions around a designated treatment volume, while minimizing exposure to vital organs. Because the intended dose distributions are sensitive to the assumed treatment geometry, the new del...