González et al. (2003) have reported the discovery of an anomalous radiation component from ≈ 1 – 200 MeV in GRB 941017. This component varies independently of and contains > ∼ 3× the energy found in the prompt ∼ 50 keV – 1 MeV radiation component that is well described by the relativistic synchrotron-shock model. Acceleration of hadrons to very high energies can give rise to two additional emi...

We developed a new technique to measure the electron beam energy centroid and spread. It takes advantage of a sharp feature in the Advanced Photon Source (APS) diagnostic: undulator spectrum, the drop-off in the angle-integrated flux near its fundamental photon energy. The measurement technique has a high resolution and is nearly independent of the storage ring lattice functions. In this work, ...

A novel treatment modality termed energy modulated photon radiotherapy (EMXRT) was investigated. The first step of EMXRT was to determine beam energy for each gantry angle/anatomy configuration from a pool of photon energy beams (2 to 10 MV) with a newly developed energy selector. An inverse planning system using gradient search algorithm was then employed to optimize photon beam intensity of v...

We present a new external-beam radiation therapy system using very-high-energy (VHE) electron/photon beams generated by a centimeter-scale laser plasma accelerator built in a robotic system. Most types of external-beam radiation therapy are delivered using a machine called a medical linear accelerator driven by radio frequency (RF) power amplifiers, producing electron beams with an energy range...

background: monte carlo (mc) modeling of a linear accelerator is a prerequisite for monte carlo dose calculations in external beam radiotherapy. in this study, a simple and efficient model was developed for elekta sl-25 linear accelerator using mcnp4c monte carlo code materials and methods: the head of elekta sl-25 linac was simulated for 6 and 18 mv photon beams using mcnp4c mc code. energy sp...

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,...

Purpose: In the last years, some studies investigated dosimetric benefits of a free flattening filter for the photon mode in the radiotherapy field. This study aims to provide a theoretical study published and analysis of basic dosimetric properties for a Saturne 43 Linac head to implement free flattening filter beams clinically. Material and Methods: Thi...