We describe a method for computing a continuous time estimate of dynamic changes in tracer density using list mode PET data. The tracer density in each voxel is modeled as an inhomogeneous Poisson process whose rate function can be represented using a cubic B-spline basis. An estimate of these rate functions is obtained by maximizing the likelihood of the arrival times of each detected photon p...

A new algorithm for the compression of dynamic positron emission tomography (PET) data is presented. It consists of a temporal compression stage based on the application of principal component analysis (PCA) directly to the PET sinograms to reduce the dimensionality of the data. This is followed by a spatial compression stage using JPEG 2000 to each PCA channel weighted by the signal in each ch...

The radiation dose reduction without sacrificing the image quality as an important issue has raised the attention of CT manufacturers and different automatic exposure control (AEC) strategies have been adopted in their products. In this paper, we focus on the strategy of tube current modulation. It is deduced based on the signal-to-noise (SNR) of the sinogram. The main idea behind the proposed ...

This paper seeks to extend the Fourier space properties of the discrete Radon transform, R(t,m), proposed by Matus and Flusser in [1], to expanded discrete projections, R(k, θ), where the wrapping of rays is removed. This expanded mode yields projections more akin to the continuous space sinogram. It is similar to the Mojette transform defined in [2], but has a pre-determined set of discrete pr...

We have been developing Monte Carlo Techniques for calculating primary and scatter photon distributions in PET. Our first goal has been to accelerate the Monte Carlo Code for fast PET simulation. Our second goal has been to use the simulation to analyze scatter effects in PET and explore the potential for eventual use in scatter correction of clinical 3-D PET studies. We have reduced the execut...

The authors describe and demonstrate a hierarchical reconstruction algorithm for use in noisy and limited-angle or sparse-angle tomography. The algorithm estimates an object's mass, center of mass, and convex hull from the available projections, and uses this information, along with fundamental mathematical constraints, to estimate a full set of smoothed projections. The mass and center of mass...

BACKGROUND Ring artifacts are the concentric rings superimposed on the tomographic images often caused by the defective and insufficient calibrated detector elements as well as by the damaged scintillator crystals of the flat panel detector. It may be also generated by objects attenuating X-rays very differently in different projection direction. Ring artifact reduction techniques so far report...

The Fourier Rebinning (FORE), which sorts 3D data into 2D data, requires that the 3D sinogram is previously corrected for non-quantitative physical effects. So, 2D sinograms are no longer Poisson distributed, an assumption behind OSEM (Ordered Subsets Expectation Maximization). This means that whenever data are corrected and OSEM is the reconstruction algorithm, the need to restore the Poisson ...