Background: External beam radiation therapy is often administered to patients implanted with silicone gel breast prosthesis. The aim of this study was to investigate the influence of silicone gel breast prosthesis on photon dose distributions. In the event of recurrence, the oncologist may be forced to irradiate through the prosthetic device. To quantify the dose enhancement or reduction below ...

the monte carlo method can be used to describe any technique that approximates solutions to quantitative problems through statistical sampling. this method is considered to be the most accurate method for dose calculation in radiotherapy. for complete modeling of a linear accelerator, it is required that the manufactured information covers all data, but some data such as primary electron energy...

background: during radiotherapy treatment, critical organs are shielded using lead and cerrobend blocks. the objective of this study is to compare the effects of lead and cerrobend shielding blocks on incident photon beam. methods: collimator scatter factors were measured for open square fields (3 x 3 cm to 40 x 40 cm) defined by collimator jaws and for fields blocked down to smaller asymmetric...

background: physical wedges are still widely used as beam modifiers in external beam radiotherapy. however the presence of them in the beam trace may cause beam hardening which may not be considered in many treatment planning systems. the aim of this study is to investigate the beam hardening effect generated by physical wedges via different beam quality indexes as photon spectrum, half value l...

Background: Physical wedges are still widely used as beam modifiers in external beam radiotherapy. However the presence of them in the beam trace may cause beam hardening which may not be considered in many treatment planning systems. The aim of this study is to investigate the beam hardening effect generated by physical wedges via different beam quality indexes as photon spectrum, half value l...

background: the presence of a wedge filter in the beam trajectory can modify the beam quality and cause some changes in the dosimetry parameters which are usually difficult to be measured directly and accurately. material and methods: in this study the mcnp-4c monte carlo code was used to simulate the 9 mv photon beam generated by a linear accelerator. upon getting a good agreement between the ...

Introduction: In radiation therapy, knowing the dose rates to healthy organs and tumors is beneficial, and thermoluminescent dosimeter (TLD) allows for this possibility. This study was aimed at determining the dose-response differences of TLDs in various types of radiation, energy levels, and dose rate calibrated with other types of radiation beams and energy and dose levels. Materials and Meth...

Objective: The aim of the present study is to simulate 6 MV and 18 MV photon beam energies of a Siemens Primus Plus medical linear accelerator (Linac) and to verify the simulation by comparing the results with the measured data.Methods: The main components of the head of Siemens Primus Plus linac were simulated using MCNPX Monte Carlo (MC) code. To verify the results, experimental data of perce...

Purpose: To investigate the energy dependence/spectral sensitivity of silicon diodes designed for small-field dosimetry and obtain response factors (RFs) for arbitrary photon spectra using Monte Carlo (MC) simulations.   Methods: The EGSnrc user-code DOSRZnrc was used to calculate the dose deposition in water and in the active volume of a stereotactic diode f...

Introduction: During treatment of breast cancer, Radiotherapy to the Supraclavicular fossa region results in absorption of radiation by the thyroid gland and consequently leads to hypothyroidism in 40% of patients. The aim of this study was to compare thyroid gland radiation absorption during radiotherapy with different anterior-posterior beam radiation of 6-15 and 15-15 MV pho...