background: the monte carlo method is the most accurate method for simulation of radiation therapy equipment. the linear accelerators are currently the most widely used machines in radiation therapy centers. methods: in this work, a monte carlo modelling of the siemens oncor linear accelerator in 6 mv and 18 mv beams was performed. the results of simulation were validated by measurements in wat...

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...

Modern radiotherapy relies on accurate dose delivery to the prescribed target volume. The ICRU has recommended an overall accuracy in tumour dose delivery of ±5%, based on an analysis of dose response data and on an evaluation of errors in dose delivery in a clinical setting. Considering all uncertainties involved in the dose delivery to the patient, the ±5% accuracy recommendation is by no mea...

We study electron-positron in-flight annihilation as a potential source of quasi-monoenergetic photon (or gamma-ray) beams. A high-intensity tunable-energy (1.515 MeV) gamma source has many potential uses in medical, industrial and security applications. Several electron-positron collision geometries are considered: a) head-on; b) collinear; and c) positron beam incident on a fixed electron tar...

Abstract Magnetic field amplification during the nonlinear stage of current filamentation instability excited by ultra-relativistic electron beams is investigated with a two-dimensional electromagnetic particle-in-cell (PIC) simulation code, special attention paid to effects plasma ions and system size. The effect shown be significant enhanced magnetic beam energy deposition are found due cavit...

When the PDD (percentage depth dose) in the megavoltage beams is measured in the water phantom using the dosimetry system, the polarity and ion recombination effects of ionization chambers with depth in water are not usually taken into consideration. The polarity and ion recombination effects may vary depending on the radiation type and spectrum, which vary with depth in water [1-4]. If those e...

We examine the dynamics of electron beams that, in free space, are self-accelerating, presence an additional magnetic field. focus our attention case Airy that follow parabolic trajectories and generalized classes associated with power-law trajectories. study interplay between beam self-acceleration circular motion caused by In beams, using integral representation, we find closed-form solutions...