Iterative PET image reconstructions can improve quantitation accuracy by explicitly modeling photon-limited nature and physical effects of coincident photons. Geometric model in iterative reconstructions defines the mapping between image and sinogram domains based on scanners geometry, which affects the accuracy of image results and the convergence rate of reconstruction algorithms. This paper ...

Introduction A system matrix with high accuracy is essential when applying iterative reconstruction algorithms like MLEM and OSEM in PET imaging. However, using Monte Carlo simulations may not always be feasible, as they take a considerable amount of time. The detector response function (DRF) model has proven to be a good alternative [1]. Further accelerating the execution of this model is bene...

Abbreviations 2D, 3D 2-dimensional, 3-dimensional CZT cadmium zinc telluride EKG electric signal from the heart FBP filtered backprojection FOV field-of-view GE General Electric Ge(Li) germanium detector doped with lithium MLEM maximum likelihood expectation maximization NaI(Tl) sodium iodine doped with thallium NM nuclear medicine OSEM ordered subset expectation maximization PET positron emiss...

Limited-angle positron emission tomography systems can be placed next to the anatomical area of interest, improving their spatial resolution and diagnostic sensitivity. However, the incomplete angular sampling makes the reconstruction process susceptible to image artifacts and anisotropic spatial resolution. In this work, I show that combining total variation (TV) minimization with the maximum ...

At the experimental heavy ion therapy facility at the GSI Darmstadt an in-beam PET scanner is operated for quality assurance monitoring simultaneously to the therapeutic irradiation. A fully 3D maximum likelihood expectation maximization (MLEM) reconstruction algorithm has been developed and adapted to the special conditions of in-beam PET [1]. The system response function (system matrix) for t...

Imaging distributions of radioactive sources plays a substantial role in nuclear medicine as well monitoring waste and its deposit. Coded Aperture has been proposed an alternative to parallel or pinhole collimators, but requires image reconstruction extra step. Multiple methods with varying run time computational complexity have proposed. Yet, no quantitative comparison between the different ca...

Background: Photon attenuation as an inevitable physical phenomenon influences on the diagnostic information of SPECT images and results to errors in accuracy of quantitative measurements. This can be corrected via different physical or mathematical approaches. As the correction equation in mathematical approaches is nonlinear, in this study a new method of linearization called ‘Piece Wise Line...

A sparsity-exploiting algorithm intended for few-view single photon emission computed tomography (SPECT) reconstruction is proposed and characterized. The algorithm models the object as piecewise constant subject to a blurring operation. To validate that the algorithm closely approximates the true object in the noiseless case, projection data were generated from an object assuming this model an...

As a new three-dimensional breast imaging technique, breast tomosynthesis allows the reconstruction of an arbitrary set of planes in the breast from a limited-angle series of x-ray projection images. The breast tomosynthesis technique has been demonstrated as promising to improve early breast cancer detection. This paper represents a preliminary phantom study and computer simulation results of ...

Iterative reconstruction algorithms like MLEM (Maximum Likelihood Expectation Maximization) can be regularized using a weighted roughness penalty term according to certain a priori assumptions of the desired image. In the MRP (Median Root Prior) algorithm the penalty is set according to the deviance of a pixel from the local median. This allows both noise reduction and edge preservation. The pr...