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,...

radiotherapy dose calculations can be evaluated by monte carlo (mc) simulations with acceptable accuracy for dose prediction in complicated treatment plans. in this work, standard, livermore and penelope electromagnetic (em) physics packages of geant4 application for tomographic emission (gate) 6.1 were compared versus monte carlo n-particle extended (mcnpx) 2.6 in simulation of 6 mv photon lin...

Introduction: Photon contamination is a restriction on treatment with electron that increase dose to healthy tissue below the tumor. The aim of this study is to reduce the photon contamination using a magnet system. Materials and Methods: A mini-applicator equipped with two neodymium boron permanent magnets was designed which make it possible to adjust the d...

This study investigated radiation dose variations in pre-clinical irradiation due to the photon beam energy and presence of tissue heterogeneity. Based on the same mouse computed tomography image dataset, three phantoms namely, heterogeneous, homogeneous and bone homogeneous were used. These phantoms were generated by overriding the relative electron density of no voxel (heterogeneous), all vox...

  Introduction:    Multileaf collimators (MLCs) are computer-controlled devices which are Useful and cost-effective tools for conformal therapy and intensity modulation radiotherapy (IMRT). Nowadays MLCs are important and standard configuration of the new medical linear accelerators which are substitute of conventional Blocks and has eliminated the ...

1. INTRODUCTION X-ray sources on next generation low emittance/high brilliance synchrotrons such as the 7-GeV Advanced Photon Source (APS) (1) have unique properties which directly affect the design of the front end of the beam line. The most striking of these are the large peak photon power densities expected for the insertion device (ID) x-ray sources. Undulators. for example. can have highly...

The third-generation synchrotron radiation (SR) facilities are storage ring-based facilities with many insertion devices and photon beamlines, and have low injection beam power, but extremely high stored beam power. The fourth-generation X-ray free electron laser (FEL) facilities are based on an electron Linac with a long undulator and have high injection beam power. Due to its electron and pho...

Most of the treatment units, both new and old models, are equipped with a megavoltage portal imager but its use for volumetric imaging is limited. This is mainly due to the poor image quality produced by the high-energy treatment beam (> 6MV). A linac at our center is equipped with a prototype 2.5 MV imaging beam. This study evaluates the feasibility of low-dose megavoltage cone-beam imaging wi...

We coherently probe a quantum dot that is strongly coupled to a photonic crystal nano-cavity by scattering of a resonant laser beam. The coupled system’s response is highly nonlinear as the quantum dot saturates with nearly one photon per cavity lifetime. This system enables large amplitude and phase shifts of a signal beam via a control beam, both at single photon levels. We demonstrate photon...