The qualitative and quantitative accuracy of SPECT images is degraded by physical factors of attenuation, Compton scatter and spatially varying collimator geometric response. This paper presents a 3D ray-tracing technique for modelling attenuation, scatter and geometric response for SPECT imaging in an inhomogeneous attenuating medium. The model is incorporated into a three-dimensional projecto...

Segmented-based attenuation correction is now a widely accepted technique to reduce noise contribution of measured attenuation correction. In this paper, we present a new method for segmenting transmission images in positron emission tomography. This reduces the noise on the correction maps while still correcting for differing attenuation coefficients of specific tissues. Based on the Fuzzy C-M...

Respiratory motion is a source of degradation in positron emission tomography. As the patients cannot hold breath during the PET acquisition, spatial blurring and motion artifacts are unavoidable which may lead to wrong quantification of the data. A solution based on respiratory-gating and optical flow based correction of the PET data is proposed. This includes deformation of the CT data for ac...

Methods: Fifty-one patients were imaged with a simultaneous gated transmission-emission tomographic system. Each patient had biplane contrast ventriculography (CVG) performed within 90 days of the SPECT study. The tomographic data was acquired over 16 frames/cycle, 64x64 matrix, 6.3mm pixels, over 360 degrees for 16 minutes duration. Attenuation corrected (AC) emission images were reconstructed...

This work deals with the single photon emission computed tomography (SPECT) reconstruction process. As a SPECT measurement also depends on unknown attenuation properties of the tissue, such a process is challenging. Furthermore, the given attenuation may not be a good approximation to the true attenuation field. Reasons are repositioning or movement of the patient such as relaxation during scan...

We report on extended measurements and theory on the recently developed monolithic wavelength demultiplexer consisting of voltage tunable superlattice p-i-n photodetectors in a waveguide configuration. This includes a reduced wavelength spacing, an investigation of the polarization dependence of the crosstalk and bit-error-rate measurements for various crosstalk levels. We show that the device ...

Surface soil moisture is a key variable needed to understand and predict the climate. L-band microwave radiometry seems to be the best technique to remotely measure the soil moisture content, since the influence of other effects such as surface roughness and vegetation is comparatively small. This work describes a numerical model developed to efficiently compute the four elements of the Stokes ...