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...

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,...

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-...

Introduction: Intraoperative electron radiotherapy (IOERT) is an IORT technique in which electron beams with different nominal energies are used for irradiation of microscopic residual of tumor bed after surgery. Application of a shielding disk, which is positioned under the target volume, for protecting the normal tissues such as pectoral muscle, lung, and heart is one of the a...

A new method is proposed for scatter-correction of cone-beam CT images. A coarse reconstruction is used in initial iteration steps. Modelling of the x-ray tube spectra and detector response are included in the algorithm. Photon diffusion inside the imaging subject is calculated using the Monte Carlo method. Photon scoring at the detector is calculated using forced detection to a fixed set of no...

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...

The aim is to study beam characteristics at large distances when focusing on the electron component. In particular, to investigate the utility of spoilers with various thicknesses as an electron source, as well as the effect of different spoiler-to-surface distances (STSD) on the beam characteristics and, consequently, on the dose in the superficial region. A MC model of a 15 MV Varian accelera...

The assumption of cylindrical symmetry in radiotherapy accelerator models can pose a challenge for precise Monte Carlo modeling. This assumption makes it difficult to account for measured asymmetries in clinical dose distributions. We have performed a sensitivity study examining the effect of varying symmetric and asymmetric beam and geometric parameters of a Monte Carlo model for a Siemens PRI...