Purpose: A method for determination of effective transmission factors of the Varian Enhanced Dynamic Wedge (EDW) is investigated. Methods and Material: The model assumes that the EDW factor equals the fraction of monitor units delivered to the geometrical center of the beam. This ”MU fraction approximation” is verified by comparing its predictions with measurements of a series of symmetric and ...

introduction: esophageal cancer is one of the most frequently occurring cancers in iran and having a  high  incidence  rate  among  other  countries.  radiotherapy  is  one  of  the  three  methods  (surgery,  radiotherapy and chemotherapy) for radical or palliative treatment of esophageal cancer. in this method  of treatment, the organs such as heart and spinal cord are regarded as organs at r...

Introduction: The aim of this study is to investigate the effect of partially used high photon energies on dosimetric parameters and integral doses of nasopharynx IMRT plans.   Materials and Methods: Two 7 coplanar IMRT plan were created for eleven patients (6 MV only IMRT plan in both phase1 and phase2 and 6 MV phase1-mixed energies (6 MV and 15 MV) phase2...

Highly attenuating radiation treatment couches are no longer useful in the present era of radiotherapy utilizing IMRT and IGRT. Carbon fibers couch tops with its high tensile strength and low density present a useful alternative. The objective of the current study was to quantify the attenuation of megavoltage photons through a Brainlab imaging couch top and headrest at various angles and field...

Background: The aim of this work was to study the output factors for Linac using different ionization chambers and build up caps. Materials and Methods: Output factors were measured for open square fields (3 × 3 cm to 40 × 40 cm) defined by collimator jaws for 6 and 15 MV photon beams from a Varian Clinac 2100C accelerator were measured. The measurements in air were performed using Com...

The accuracy of the photon convolution/superposition dose algorithm employed in a commercial radiation treatment planning system was evaluated for conditions simulating tangential breast treatment. A breast phantom was fabricated from machineable wax and placed on the chest wall of an anthropomorphic phantom. Radiographic film was used to measure the dose distribution at the axial midplane of t...

one of the applications of gold nanoparticles (gnps) in medicine is radiation dose-enhancing effect. although there are many simulations, in vitro and in vivo evidence that gnps can enhance significantly the radiation dose effect of orthovoltage beams. these beams compared with megavoltage (mv) beams, have limited applications in radiotherapy. in order to evaluate gnps radiosensitization perfor...

Background: Breast-conserving surgery (BCS) followed by radiotherapy (RT) is the standard of care for women with breast cancer. Evidence shows that RT dose to the heart can result in ischemic heart disease. In this study we compared 3 different RT techniques were for heart, left anterior descending coronary artery (LAD) and lung doses in left breast cancer patients after breast-conserving surge...

background: two protocols of aapm tg-51 and iaea trs-398 were compared followed by a measurement and monte carlo simulation of beam quality correction factor, kq, aapm tg-51 and iaea trs-398 protocols were compared for the absorbed dose to water for dw, and kq parameters. materials and methods: dose measurements by either protocols were performed with cylindrical and plane parallel chambers for...