Objective: Using Megavoltage photons generated by medical linear accelerator is a common modality for the treatment of malignant. The crucial problem for using photon beams >8MV is the photoneutron yields that increase the risk of secondary cancer that treated with high-energy photon beams. The contaminated neutrons produced in different components of the accelerator head and rely on many param...

Objective: Using Megavoltage photons generated by medical linear accelerator is a common modality for the treatment of malignant. The crucial problem for using photon beams >8MV is the photoneutron yields that increase the risk of secondary cancer that treated with high-energy photon beams. The contaminated neutrons produced in different components of the accelerator head and rely on many param...

Background: The aim of present study was to analyze the effectiveness of electron filters in the Telecobalt radiotherapy treatment by simulation technique.  Materials and Methods: The BEAMnrc Monte Carlo code was used to simulate the electron filters of thickness of 0.5 gm/cm2 below the trimmer bar for 35 × 35 cm2 field size in Theratron Equinox-80 telecobalt unit. The electron filters were mad...

Bobbi Roop Advanced Photon Source Argonne National Laboratory Argonne,IL 60439 An x-ray photoemission spectroscopic study was undertaken to compare the cleaning of the Advanced Photon Source (APS) aluminum extrusion storage ring vacuum chambers after machining with and ~thout water soluble coolants. While there was significant contamination left by the coolants, the cleaning process was capable...

BACKGROUND Megavoltage beams used in radiotherapy are contaminated with secondary electrons. Different parts of linac head and air above patient act as a source of this contamination. This contamination can increase damage to skin and subcutaneous tissue during radiotherapy. Monte Carlo simulation is an accurate method for dose calculation in medical dosimetry and has an important role in optim...

PURPOSE To report the development and validation of a technique of dual tracer single-photon emission CT brain imaging using technetium-99m hexamethylpropyleneamine oxime and iodine-123 iodoamphetamine agents and the application of this technique in patients with a variety of diagnoses. METHODS Contamination between the two isotopes' energy windows was calculated by opening both energy window...

Much of the algorithms used to calculate dose distributions for photon beams generated by clinical electron linacs (Zhou et al. 2010, Sikora and Alber 2009, Tillikainen 2009) consider three particle sources: a photon source corresponding to Bremsstrahlung in the target (primary source), a second photon source that takes into account those photons produced by scattering into the primary collimat...

Background: The electron contamination may reduce or even diminish the skin sparing property of the megavoltage beam. The detailed characteristics of contaminant electrons are presented for different field sizes and cases. Materials and Methods: The Monte Carlo code, MCNPX, has been used to simulate 18 MV photon beam from a Varian Linac-2300 accelerator. All dose measurements were car...

Platinum is one of the most common coatings used to optimize mirror reflectivity in soft X-ray beamlines. Normal operation results in optics contamination by carbon-based molecules present in the residual vacuum of the beamlines. The reflectivity reduction induced by a carbon layer at the mirror surface is a major problem in synchrotron radiation sources. A time-dependent photoelectron spectros...

ÐMeasurement of lepton contamination is achieved across a radiotherapy photon beam and peripheral doses using radiochromic ®lm. An extrapolation technique is used where several layers are suspended in air to measure incident contamination without the e€ects of phantom scatter. Surface dose was measured as 11% of Dmax for 6 MV beams at central axis and 9% for 10 MV photons for a 10 10 cm ®eld si...