BACKGROUND Megavoltage beams used in radiotherapy are contaminated with secondary electrons. Different parts of linac head and air above patient act as a source of this contamination. This contamination can increase damage to skin and subcutaneous tissue during radiotherapy. Monte Carlo simulation is an accurate method for dose calculation in medical dosimetry and has an important role in optim...

The BEAM code is used to simulate nine photon beams from three major manufacturers of medical linear accelerators (Varian, Elekta, and Siemens), to derive and evaluate estimates for the parameters of the electron beam incident on the target, and to study the effects of some mechanical parameters like target width, primary collimator opening, flattening filter material and density. The mean ener...

abstract nowruzak (salvia leriifolia) of lamiaceae family has a good capability for domestication in khorasan’s natural habitats. in order to investigate the effect of sowing design and depth in seedling emergence and permanence, a split plot experiment based on a randomized complete block design was performed with three replications. results indicated sowing design in all three parameters, sow...

PURPOSE To obtain the absolute dose-rate distribution in liquid water for all six cup-shaped Leipzig applicators by means of an experimentally validated Monte Carlo (MC) code. These six applicators were used in high-dose-rate (HDR) afterloaders with the "classic" and v2 (192)Ir sources. The applicators have an inner diameter of 1, 2, and 3 cm, with the source traveling parallel or perpendicular...

New technologies in cancer radiotherapy need a more accurate computation of the dose delivered in the radiotherapeutical treatment plan, and it is important to integrate sophisticated mathematical models and advanced computing knowledge into the treatment planning (TP) process. We present some results about using Monte Carlo (MC) codes in dose calculation for treatment planning. A distributed c...

When the PDD (percentage depth dose) in the megavoltage beams is measured in the water phantom using the dosimetry system, the polarity and ion recombination effects of ionization chambers with depth in water are not usually taken into consideration. The polarity and ion recombination effects may vary depending on the radiation type and spectrum, which vary with depth in water [1-4]. If those e...

In this work isodose curves are obtained by the use of a new dosimetric algorithm using numerical data from percentage depth dose (PDD) and the maximum absorbed dose profile, calculated by Monte Carlo in a 18 MV LINAC. The software allows reproducing the absorbed dose percentage in the whole irradiated volume quickly and with a good approximation. To validate results an 18 MV LINAC with a whole...