Introduction: The aim of this study is to investigate the effect of partially used high photon energies on dosimetric parameters and integral doses of nasopharynx IMRT plans.   Materials and Methods: Two 7 coplanar IMRT plan were created for eleven patients (6 MV only IMRT plan in both phase1 and phase2 and 6 MV phase1-mixed energies (6 MV and 15 MV) phase2...

The separation ∆ peak between two peaks in the gamma-ray pulse profile is calculated as a function of energy for several polar cap models with curvature-radiation-induced cascades. The Monte Carlo results are interpreted with the help of analytical approximations and discussed in view of the recent data analysis for the Vela pulsar (Kanbach 1999). We find that the behaviour of ∆ peak as a funct...

smaller than those listed in the table. The LCLS photon pulses are expected to attain unprecedented levels of brightness and brevity in the 300400eV range. Nominally, the photon pulse length will be dominated by the electron bunch length, while the performance of conventional x-ray reflecting and bandshaping optics will be limited by : 1) peak power damage, and 2) transform-limited monochromati...

Fundamental limits for photon counting and photon energy measurement are reviewed for CCD and CMOS imagers. The challenges to extend photon counting into the visible/nIR wavelengths and achieve energy measurement in the UV with specific read noise requirements are discussed. Pixel flicker and random telegraph noise sources are highlighted along with various methods used in reducing their contri...

Muon bremsstrahlung photons converted in front of the DELPHI main tracker (TPC) in dimuon events at LEP1 were studied in two photon kinematic ranges: 0.2 <Eγ ≤ 1 GeV and transverse momentum with respect to the parent muon pT < 40 MeV/c, and 1 <Eγ ≤ 10 GeV and pT < 80 MeV/c. A good agreement of the observed photon rate with predictions from QED for the muon inner bremsstrahlung was found, contra...

Background: To enhance the dose to tumor, the use of high atomic number elements has been proposed.Objective: The aim of this study is to investigate the effect of gold nanoparticle distribution on dose enhancement in tumor when the tumor is irradiated by typical monoenergetic X-ray beams by considering homogeneous and inhomogeneous distributions of gold nanoparticles (GNPs) in the tumor.Method...

Purpose: To quantify the DNA damage induced in a clinical megavoltage photon beam at various depths in and out of the field. Methods and Materials: MCNPX was used to simulate 10x10 cm and 20x20 cm 10 MV photon beams from a clinical linear accelerator. Photon and electron spectra were collected in a water phantom at depths of 2.5, 12.5 and 22.5 cm on the central axis and at off-axis points out t...

Abstract The angle-integrated flux spectrum of an undulator has sharp dropoffs at harmonic photon energies. Its derivative therefore shows pronounced peaks with rms width ∆ω/ω ~ 0.4/nN, where ω is the photon energy, n is the harmonic number, and N is the number of undulator periods. For the fundamental photon energy of the Advanced Photon Source diagnostics undulator, the derivative of the angl...

In a previous article [Phys. Rev. Lett. 117, 213201 (2016)] we have determined the angular resolved and the total energy spectrum of a positron produced via nonlinear Breit-Wheeler pair production by a high-energy photon counterpropagating with respect to a tightly focused laser beam. Here, we first generalize the results in that article by including the possibility that the incoming photon is ...

The novel possibilities of probing the photon structure and high energy limit of QCD at photon colliders are summarised. We discuss the photon structure function F γ 2 (x, Q 2), the gluon distribution in the photon and the spin dependent structure function g γ 1 (x, Q 2) of the photon and emphasise advantages of the pho-ton colliders for measuring these quantities. The possibility of probing th...