Linear array implementation of the EM algorithm for PET image reconstruction
Abstract
The PET image reconstruction based on the EM algorithm has several attractive advantages over the conventional convolution back projection algorithms. However, the PET image reconstruction based on the EM algorithm is computationally burdensome for today`s single processor systems. In addition, a large memory is required for the storage of the image, projection data, and the probability matrix. Since the computations are easily divided into tasks executable in parallel, multiprocessor configurations are the ideal choice for fast execution of the EM algorithms. In tis study, the authors attempt to overcome these two problems by parallelizing the EM algorithm on a multiprocessor systems. The parallel EM algorithm on a linear array topology using the commercially available fast floating point digital signal processor (DSP) chips as the processing elements (PE`s) has been implemented. The performance of the EM algorithm on a 386/387 machine, IBM 6000 RISC workstation, and on the linear array system is discussed and compared. The results show that the computational speed performance of a linear array using 8 DSP chips as PE`s executing the EM image reconstruction algorithm is about 15.5 times better than that of the IBM 6000 RISC workstation. The novelty of the scheme is its simplicity. Themore »
 Authors:
 Indian Institute of Science, Bangalore (India)
 Publication Date:
 OSTI Identifier:
 119014
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: IEEE Transactions on Nuclear Science; Journal Volume: 42; Journal Issue: 4; Other Information: PBD: Aug 1995
 Country of Publication:
 United States
 Language:
 English
 Subject:
 55 BIOLOGY AND MEDICINE, BASIC STUDIES; 99 MATHEMATICS, COMPUTERS, INFORMATION SCIENCE, MANAGEMENT, LAW, MISCELLANEOUS; POSITRON COMPUTED TOMOGRAPHY; IMAGE PROCESSING; ALGORITHMS; ARRAY PROCESSORS; PARALLEL PROCESSING; IBM COMPUTERS; PERFORMANCE; COMPARATIVE EVALUATIONS; COMPUTER ARCHITECTURE
Citation Formats
Rajan, K., Patnaik, L.M., and Ramakrishna, J. Linear array implementation of the EM algorithm for PET image reconstruction. United States: N. p., 1995.
Web. doi:10.1109/23.467723.
Rajan, K., Patnaik, L.M., & Ramakrishna, J. Linear array implementation of the EM algorithm for PET image reconstruction. United States. doi:10.1109/23.467723.
Rajan, K., Patnaik, L.M., and Ramakrishna, J. 1995.
"Linear array implementation of the EM algorithm for PET image reconstruction". United States.
doi:10.1109/23.467723.
@article{osti_119014,
title = {Linear array implementation of the EM algorithm for PET image reconstruction},
author = {Rajan, K. and Patnaik, L.M. and Ramakrishna, J.},
abstractNote = {The PET image reconstruction based on the EM algorithm has several attractive advantages over the conventional convolution back projection algorithms. However, the PET image reconstruction based on the EM algorithm is computationally burdensome for today`s single processor systems. In addition, a large memory is required for the storage of the image, projection data, and the probability matrix. Since the computations are easily divided into tasks executable in parallel, multiprocessor configurations are the ideal choice for fast execution of the EM algorithms. In tis study, the authors attempt to overcome these two problems by parallelizing the EM algorithm on a multiprocessor systems. The parallel EM algorithm on a linear array topology using the commercially available fast floating point digital signal processor (DSP) chips as the processing elements (PE`s) has been implemented. The performance of the EM algorithm on a 386/387 machine, IBM 6000 RISC workstation, and on the linear array system is discussed and compared. The results show that the computational speed performance of a linear array using 8 DSP chips as PE`s executing the EM image reconstruction algorithm is about 15.5 times better than that of the IBM 6000 RISC workstation. The novelty of the scheme is its simplicity. The linear array topology is expandable with a larger number of PE`s. The architecture is not dependant on the DSP chip chosen, and the substitution of the latest DSP chip is straightforward and could yield better speed performance.},
doi = {10.1109/23.467723},
journal = {IEEE Transactions on Nuclear Science},
number = 4,
volume = 42,
place = {United States},
year = 1995,
month = 8
}

Purpose: To investigate the performance of a new penalizedlikelihood PET image reconstruction algorithm using the 1{sub 1}norm totalvariation (TV) sum of the 1st through 4thorder gradients as the penalty. Simulated and brain patient data sets were analyzed. Methods: This work represents an extension of the preconditioned alternating projection algorithm (PAPA) for emissioncomputed tomography. In this new generalized algorithm (GPAPA), the penalty term is expanded to allow multiple components, in this case the sum of the 1st to 4th order gradients, to reduce artificial piecewise constant regions (“staircase” artifacts typical for TV) seen in PAPA images penalized with only the 1stmore »

Towards the clinical implementation of iterative lowdose conebeam CT reconstruction in imageguided radiation therapy: Cone/ring artifact correction and multiple GPU implementation
Purpose: Compressed sensing (CS)based iterative reconstruction (IR) techniques are able to reconstruct conebeam CT (CBCT) images from undersampled noisy data, allowing for imaging dose reduction. However, there are a few practical concerns preventing the clinical implementation of these techniques. On the image quality side, data truncation along the superior–inferior direction under the conebeam geometry produces severe cone artifacts in the reconstructed images. Ring artifacts are also seen in the halffan scan mode. On the reconstruction efficiency side, the long computation time hinders clinical use in imageguided radiation therapy (IGRT). Methods: Image quality improvement methods are proposed to mitigate the conemore » 
Derivation and implementation of a conebeam reconstruction algorithm for nonplanar orbits
Smith and Grangeat derived a conebeam inversion formula that can be applied when a nonplanar orbit satisfying the completeness condition is used. Although Grangeat's inversion formula is mathematically different from Smith's, they have similar overall structures to each other. The contribution of this paper is twofold. First, based on the derivation of Smith, the authors point out that Grangeat's inversion formula and Smith's can be conveniently described using a single formula (the SmithGrangeat inversion formula) that is in the form of spacevariant filtering followed by conebeam backprojection. Furthermore, the resulting formula is reformulated for data acquisition systems with a planarmore » 
Geneticalgorithm implementation of atomic potential reconstruction from differential electron scattering cross sections
We demonstrate the successful implementation of genetic algorithm for the retrieval of atomic potentials using elastic differential cross sections (DCSs) between free electrons and atomic ions for electron energies from a few to several tens of electron volts. Since the DCSs over this energy region can be extracted from lasergenerated highenergy photoelectron momentum spectra, the results suggest that infrared lasers can be used to image the target structure. Extending to molecular targets, in particular, to transient molecules created by an earlier pump pulse, our results suggest that fewcycle infrared probe lasers can be used for dynamic chemical imaging with temporalmore » 
Clinical implementation of a digital tomosynthesisbased seed reconstruction algorithm for intraoperative postimplant dose evaluation in low dose rate prostate brachytherapy
Purpose: The low dose rate brachytherapy procedure would benefit from an intraoperative postimplant dosimetry verification technique to identify possible suboptimal dose coverage and suggest a potential reimplantation. The main objective of this project is to develop an efficient, operatorfree, intraoperative seed detection technique using the imaging modalities available in a low dose rate brachytherapy treatment room. Methods: This intraoperative detection allows a complete dosimetry calculation that can be performed right after an I125 prostate seed implantation, while the patient is still under anesthesia. To accomplish this, a digital tomosynthesisbased algorithm was developed. This automatic filtered reconstruction of the 3D volumemore »