A T-shaped fiber-optic phantom-dosimeter system was developed using square scintillating optical fibers, a lens system, and a CMOS image camera. Images of scintillating light were used to simultaneously measure the transverse and longitudinal distributions of absorbed dose of a 6 MV photon beam with field sizes of 1 × 1 and 3 × 3 cm(2). Each optical fiber has a very small sensitive volume and t...

The percentage depth dose in the build-up region and the surface dose for the 6-MV photon beam from a Varian Clinac 23EX medical linear accelerator was investigated for square field sizes of 5 × 5, 10 × 10, 15 × 15 and 20 × 20 cm(2)using the EGS4nrc Monte Carlo (MC) simulation package. The depth dose was found to change rapidly in the build-up region, and the percentage surface dose increased p...

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 opt...

Background: The purpose of this study was to evaluate nodal irradiation with conventional three-field's technique. Materials and Methods: Fifty patients with breast cancer were enrolled in this study. Computed tomography scans in the supine treatment position were imported into a treatment planning system. Levels I-III axillary and supraclavicular nodes were identified and their depths to the a...

The purpose of this study was to evaluate proton depth dose perturbation caused by a radio-opaque hydrogel fiducial marker. Electronic proton stopping powers in the hydrogel were calculated for energies 0.5-250 MeV, and Monte Carlo simulations were generated of hydrogel vs. gold markers placed at various water phantom depths in a generic proton beam. Across the studied energy range, the gel/wat...