Total variation superiorization schemes in proton computed tomography image reconstruction.

Med Phys

Centre for Medical Radiation Physics, University of Wollongong, Wollongong, New South Wales 2522, Australia.

Published: November 2010

Purpose: Iterative projection reconstruction algorithms are currently the preferred reconstruction method in proton computed tomography (pCT). However, due to inconsistencies in the measured data arising from proton energy straggling and multiple Coulomb scattering, the noise in the reconstructed image increases with successive iterations. In the current work, the authors investigated the use of total variation superiorization (TVS) schemes that can be applied as an algorithmic add-on to perturbation-resilient iterative projection algorithms for pCT image reconstruction.

Methods: The block-iterative diagonally relaxed orthogonal projections (DROP) algorithm was used for reconstructing GEANT4 Monte Carlo simulated pCT data sets. Two TVS schemes added on to DROP were investigated; the first carried out the superiorization steps once per cycle and the second once per block. Simplifications of these schemes, involving the elimination of the computationally expensive feasibility proximity checking step of the TVS framework, were also investigated. The modulation transfer function and contrast discrimination function were used to quantify spatial and density resolution, respectively.

Results: With both TVS schemes, superior spatial and density resolution was achieved compared to the standard DROP algorithm. Eliminating the feasibility proximity check improved the image quality, in particular image noise, in the once-per-block superiorization, while also halving image reconstruction time. Overall, the greatest image quality was observed when carrying out the superiorization once per block and eliminating the feasibility proximity check.

Conclusions: The low-contrast imaging made possible with TVS holds a promise for its incorporation into future pCT studies.

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2980547PMC
http://dx.doi.org/10.1118/1.3504603DOI Listing

Publication Analysis

Top Keywords

tvs schemes
12
feasibility proximity
12
total variation
8
variation superiorization
8
proton computed
8
computed tomography
8
image reconstruction
8
iterative projection
8
drop algorithm
8
spatial density
8

Similar Publications

Article Synopsis
  • - Hemorrhage is the main cause of preventable death in trauma situations, leading to military and civilian advancements in medical practices, particularly through the use of tourniquets to manage extremity bleeding and save lives.
  • - While tourniquets have significantly decreased deaths from bleeding in military settings, noncompressible hemorrhage still poses a major risk, especially before patients receive definitive medical care.
  • - The study explores using a small, disposable pressure monitor during resuscitative endovascular balloon occlusion of the aorta (REBOA) to enhance blood pressure monitoring, facilitate better resuscitation practices, and reduce the need for blood products in extreme environments.
View Article and Find Full Text PDF

Low-Complexity Chase Decoding of Reed-Solomon Codes Using Channel Evaluation.

Entropy (Basel)

March 2022

College of Electronic Information and Optical Engineering, Nankai University, Tianjin 300071, China.

A novel time-varying channel adaptive low-complexity chase (LCC) algorithm with low redundancy is proposed, where only the necessary number of test vectors (TVs) are generated and key equations are calculated according to the channel evaluation to reduce the decoding complexity. The algorithm evaluates the error symbol numbers by counting the number of unreliable bits of the received code sequence and dynamically adjusts the decoding parameters, which can reduce a large number of redundant calculations in the decoding process. We provide a simplified multiplicity assignment (MA) scheme and its architecture.

View Article and Find Full Text PDF

We reveal a 2D-3D switchable lens unit that is based on a polarization-sensitive microlens array and a polarization selector unit made of an electrically suppressed helix ferroelectric liquid crystal (ESHFLC) cell. The ESHFLCs offer a high contrast ratio (∼10k∶1) between the crossed polarizers at a low applied electric field (∼1.7  V/μm) with a small switching time (<50  μs).

View Article and Find Full Text PDF

A rhythm-based authentication scheme for smart media devices.

ScientificWorldJournal

April 2015

Department of Computer Science and Engineering, Seoul National University of Science and Technology, Seoul 139-743, Republic of Korea.

In recent years, ubiquitous computing has been rapidly emerged in our lives and extensive studies have been conducted in a variety of areas related to smart devices, such as tablets, smartphones, smart TVs, smart refrigerators, and smart media devices, as a measure for realizing the ubiquitous computing. In particular, smartphones have significantly evolved from the traditional feature phones. Increasingly higher-end smartphone models that can perform a range of functions are now available.

View Article and Find Full Text PDF

Total variation superiorization schemes in proton computed tomography image reconstruction.

Med Phys

November 2010

Centre for Medical Radiation Physics, University of Wollongong, Wollongong, New South Wales 2522, Australia.

Purpose: Iterative projection reconstruction algorithms are currently the preferred reconstruction method in proton computed tomography (pCT). However, due to inconsistencies in the measured data arising from proton energy straggling and multiple Coulomb scattering, the noise in the reconstructed image increases with successive iterations. In the current work, the authors investigated the use of total variation superiorization (TVS) schemes that can be applied as an algorithmic add-on to perturbation-resilient iterative projection algorithms for pCT image reconstruction.

View Article and Find Full Text PDF

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!