The use of electronic portal imaging devices (EPIDs) is a promising method for the dosimetric verification of external beam, megavoltage radiation therapy-both pretreatment and in vivo. In this study, a previously developed EPID back-projection algorithm was modified for IMRT techniques and applied to an amorphous silicon EPID. By using this back-projection algorithm, two-dimensional dose distr...

Background: In radiation therapy with ion beams, lateral distributions of absorbed dose in the tissue are important. Heavy ion therapy, such as carbon-ion therapy, is a novel technique of high-precision external radiotherapy which has advantages over proton therapy in terms of dose locality and biological effectiveness.Methods: In this study, we used Monte Carlo method-based Geant4 toolkit to s...

Introduction: The most modern radiotherapy devices are equipped with an Electronic Portal Imaging Device (EPID) system which is located on opposite side of the machine’s head. EPID system is often used to setting up the position verification during or between radiotherapy sessions. Material and Methods: Various types of dosimeters have been used to setting up ...

Varian introduced (in 2010) the option of removing the flattening filter (FF) in their C-Arm linacs for intensity-modulated treatments. This mode, called flattening filter-free (FFF), offers the advantage of a greater dose rate. Varian's "Portal Dosimetry" is an electronic portal imager device (EPID)-based tool for IMRT verification. This tool lacks the capability of verifying flattening filter...

PURPOSE To verify the dose distribution and number of monitor units (MU) for dynamic treatment techniques like volumetric modulated single arc radiation therapy-Rapid Arc-each patient treatment plan has to be verified prior to the first treatment. The purpose of this study was to develop a patient related treatment plan verification protocol using a two dimensional ionization chamber array (Mat...

background: delivering the maximum dose to tumor while achieving the minimum dose delivery to normal tissue; is the most important goal in external radiotherapy. diode in vivo dosimetry is widely considered to be an important tool for quality improvement of patient care in external radiotherapy. uncertainty in dose delivery should fall within 5% of the prescribed dose as recommended by internat...

The aim in this study is to develop a generalized strategy for 3D dose verification of IMRT and VMAT planes using EPID transit images in combination with Monte Carlo (MC) simulations. An EPID-based dosimetric verification procedure was developed to convert EPID-measured transit images into 2D exit photon fluence by de-convoluting with the MC-simulated EPID response kernels. The present scatter ...

Dose distributions can often be significantly improved by modulating the two-dimensional intensity profile of the individual x-ray beams. One technique for delivering intensity modulated beams is dynamic multileaf collimation (DMLC). However, DMLC is complex and requires extensive quality assurance. In this paper a new method is presented for a pretreatment dosimetric verification of these inte...

PURPOSE Historically, treatment of malignant surface lesions has been achieved with linear accelerator based electron beams or superficial x-ray beams. Recent developments in the field of brachytherapy now allow for the treatment of surface lesions with specialized conical applicators placed directly on the lesion. Applicators are available for use with high dose rate (HDR)(192)Ir sources, as w...