X-ray scatter poses a significant limitation to image quality in cone-beam CT (CBCT), resulting in contrast reduction, image artifacts, and lack of CT number accuracy. We report the performance of a simple scatter correction method in which scatter fluence is estimated directly in each projection from pixel values near the edge of the detector behind the collimator leaves. The algorithm operate...

Accuracy and limitation of energy-window based scatter correction techniques have been evaluated for myocardial 201Tl SPECT by means of Monte Carlo simulation. In particular, projection view-dependency of energy distribution of the scattered photons was evaluated. Two geometrical configurations were simulated: namely a homogeneous cylindrical radioactivity located asymmetrically in a homogeneou...

The in beam dual head positron camera BASTEI (Beta Activity meaSurements at the Therapy with Energetic Ions) is used to monitor and control the applied dose distributions simultaneously to tumour irradiations with carbon ion beams at the experimental heavy ion therapy facility at GSI Darmstadt. Therefore, the PET system has been mounted directly at the treatment site. A fully 3D reconstruction ...

This study proposes a method to accurately estimate the phantom scatter factor (Sp) of arbitrary rectangular fields. We measured output doses in water and air; these measured values were based on square fields and a limited number of symmetric rectangular fields using 4 MV and 10 MV X-rays of a Varian Clinac-iX. We calculated Sp from these measured values. Then, using these Sp values, we estima...

The specification of shielding for fluoroscopic facilities in the UK is based on the determination of scatter incident on a barrier using a simple formula linking kerma area product and scatter kerma. Over the last few years there has been a move to incorporate additional copper filtration in equipment used for high dose fluoroscopic and interventional examinations, and the existing formula doe...

An x-ray computed tomography (CT) simulator based on the Monte Carlo N-particle radiation transport computer code (MCNP4C) was developed for simulation of both fan- and cone-beam CT scanners. A user-friendly interface running under Matlab 6.5.1 creates the scanner geometry at different views as MCNP4C's input file. The full simulation of x-ray tube, phantom and detectors with single-slice, mult...

Scatter in a detector and its housing can result in image degradation. Typically, such scatter leads to a low-spatial frequency 'glare' superimposed on the primary signal. We infer the glare-spread function (GSF) of an amorphous-silicon flat-panel detector via an edge-spread technique. We demonstrate that this spread (referred to as 'scatter-glare' herein) causes a low-spatial frequency drop in...

Simulations using Monte-Carlo packages are increasingly used in Nuclear Imaging, both for PET and SPECT applications. Either for modeling imaging systems or developing algorithms for analysis and improvement of image quantification. The aim of this work is the study of several scatter phenomena and the evaluation and improvement of two scatter correction compensation methods in pixelized scinti...

Abstract A scattering plate consisting of multiple lead strips is an effective tool for scatter correction and dose reduction in cone-beam CT(CBCT). Existing methods take advantage data redundancy by partially blocking cone beam from a single scan to make up perform correction. However, geometric objects with large angles during CBCT scans, existing backprojection-filteration(BPF) algorithms ca...

We virtually restore faded black and white photographic prints by the method of decomposing the image into a smooth component that contains edges and smoothed homogeneous regions, and a rough component that may include grain noise but also fine detail. The decomposition into smooth and rough components is achieved using a rational filter. Two approaches are considered; in one, the smooth compon...