In this paper we develop a new method of parabolic equation (PE) for calculation of both high-frequency and small-angle taper (or collimator) impedances. The applicability of PE in the high-frequency limit is based on the observation that in this case the contribution to impedance comes from the electromagnetic waves that catch up with the beam far from the obstacle and propagate at small-angle...

Robotic radiosurgery using more than one circular collimator can improve treatment plan quality and reduce total monitor units (MU). The rationale for an iris collimator that allows the field size to be varied during treatment delivery is to enable the benefits of multiple-field-size treatments to be realized with no increase in treatment time due to collimator exchange or multiple traversals o...

The inability to avoid rectal wall irradiation has been a limiting factor in prostate cancer treatment planning. Treatment planners must not only consider the maximum dose that the rectum receives throughout a course of treatment, but also the dose that any volume of the rectum receives. As treatment planning techniques have evolved and prescription doses have escalated, limitations of rectal d...

Electronic portal imaging devices (EPIDs) are potentially valuable tools for linear accelerator quality assurance and for measuring and analyzing geometric variations in radiation treatment delivery. Geometric analysis is more robust if referenced against an absolute position such as the isocenter (collimator axis of rotation), allowing the observer to discriminate between various setup errors ...

BACKGROUND Since December 2009 a new VMAT planning system tool is available in Oncentra MasterPlan v3.3 (Nucletron B.V.). The purpose of this study was to work out standard parameters for the optimization of prostate cancer. METHODS For ten patients with localized prostate cancer plans for simultaneous integrated boost were optimized, varying systematically the number of arcs, collimator angl...

abstract background: coherent scattering leads to diffraction effects and especially constructive interferences. theseinterferences carry some information about the molecular structure of the tissue. as breast cancer isthe most widespread cancer in women, this project evaluated the application of small anglex-ray scattering (saxs) for differentiation between normal and cancerous breast tissues....

A parametrized conceptual design for a radial collimator in neutron backscattering instrument is presented, with application to the characteristic geometry of MIRACLES spectrometer, that will be constructed at European Spallation Source (ESS). The analytic development this has considered both forward scattering (sample-analyzer) and (analyzer-detectors) pathways. All dimensions (internal extern...

In this paper we compare confocal apparatus tomography and computer tomography for medical use. Two aspects are illustrated: the process of image visualization and the dose deposition. The latter aspect is a damage factor of the object under investigation; it is why the data collection time is evaluated. Two principal tomography schemes are described and the expressions connecting the collected...

In this study, an airborne alpha detection system, which consists of a passivated implanted planar silicon (PIPS) detector and air filter, was developed. A collimator applied to the system showed enhancement in resolution degradation efficiency. The efficiency were compared analyzed evaluate performance collimator. Thus, found be more important than as determining factor performance, from viewp...