A convolution backprojection algorithm was derived by Tretiak and Metz to reconstruct two-dimensional (2-D) transaxial slices from uniformly attenuated parallel-beam projections. Using transformation of coordinates, this algorithm can be modified to obtain a formulation useful to reconstruct uniformly attenuated fan-beam projections. Unlike that for parallel-beam projections, this formulation d...

designing FIR fan filters suitable for the multibeam forming network of the wideband beamspace adaptive array. Characteristics were approximated through the combination of spectral transformation and the window method so that those beam patterns that included the sidelobe characteristics of the resulting fan filters were virtually frequency independent. Using the fan filters designed by the pro...

Background: In intensity modulated radiation therapy, cone beam computed tomography (CT) has been used to evaluate patients prior to treatment. This study conducted a comparative evaluation of the image reconstruction ability of the clinically used half-fan bowtie filter and the full-fan bowtie filter. Materals and Methods: A CT simulation marker was inserted inside a human phantom, and the pel...

1. OVERVIEW An undesirable situation could develop anytime during ERL operation, even if this could be treated as a rare event. So the protection system must be designed so that despite its occasional triggering, it must yield a controllable beam dump with ~100% probability. In mostly situations the faster dump system isthe lesser the damage could be. One typical example could be represented wh...

A primary proton beam from the CERN Super Proton Synchrotron is driven to a beryllium target (KL target). After a sweeping magnet and some collimators, a neutral beam is formed. The last collimator exit is located 126 m downstream of the target (see Fig. 1). The primary protons not interacting in the KL target are deflected by a bent crystal, forming a secondary proton beam that is transported ...

An imaging displacement sensor (IDS) has been developed that can measure the displacement with an accuracy of 30 nm in 0.03 s with the precision improving to 1 nm for averaging times of 100 s. The IDS consists simply of a light emitting diode (LED) pinhole collimator and a charge-coupled device (CCD) camera chip. The position accuracy is better than 0.05% over the few mm CCD size with deviation...

Introduction: Computed tomography (CT) has numerous applications in clinical procedures but its main problem is its high radiation dose to the patients compared to other imaging modalities using x-ray. CT delivers approximately high doses to the nearby tissues due to the scattering effect, fan beam (beam divergence) and limited collimator efficiency. The radiation dose from multi-slice scanners...

introduction bnct is an effective method to destroy brain tumoral cells while sparing the healthy tissues. the recommended flux for epithermal neutrons is 109 n/cm2s, which has the most effectiveness on deep-seated tumors. in this paper, it is indicated that using d-t neutron source and optimizing of beam shaping assembly (bsa) leads to treating brain tumors in a reasonable time where all iaea ...

In this paper, a new image reconstruction scheme is presented based on Tuy's cone-beam inversion scheme and its fan-beam counterpart. It is demonstrated that Tuy's inversion scheme may be used to derive a new framework for fanbeam and cone-beam image reconstruction. In this new framework, images are reconstructed via filtering the backprojection image of differentiated projection data. The new ...

We present an example when profile measurement and modeling of an Elekta Agility multileaf collimator (MLC) had a large effect specifically on arc therapy plan quality assurance (QA) results using ArcCheck. ArcCheck absolute dose measurements of these plans were systematically lower than planned by 3-10%. Failing QA results were seen even with unmodulated static and conformal arcs. Furthermore,...