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On few-view tomographic reconstruction with megavoltage photon beams. 2001

S Loose, and K W Leszczynski
Department of Medical Physics, Northeastern Ontario Regional Cancer Centre, Sudbury, Canada.

Currently portal imaging devices are used to obtain information on patient localization during radiation therapy treatments. Such obtained information is two dimensional in nature, limited to the plane of the captured image. It has been proposed that megavoltage computed tomography images be reconstructed to overcome this limitation. This study explores the feasibility of reconstructing tomographic images from fan-beam projection data acquired with a commercial portal imaging device on a standard radiotherapy linear accelerator. Several CT reconstruction algorithms are examined as to their performance and suitability for applications in radiation therapy verification. The results show that it is possible, using some of the iterative reconstruction techniques, to obtain an image useful for patient localization from only several (< or =10) projection views.

UI MeSH Term Description Entries
D007091 Image Processing, Computer-Assisted A technique of inputting two-dimensional or three-dimensional images into a computer and then enhancing or analyzing the imagery into a form that is more useful to the human observer. Biomedical Image Processing,Computer-Assisted Image Processing,Digital Image Processing,Image Analysis, Computer-Assisted,Image Reconstruction,Medical Image Processing,Analysis, Computer-Assisted Image,Computer-Assisted Image Analysis,Computer Assisted Image Analysis,Computer Assisted Image Processing,Computer-Assisted Image Analyses,Image Analyses, Computer-Assisted,Image Analysis, Computer Assisted,Image Processing, Biomedical,Image Processing, Computer Assisted,Image Processing, Digital,Image Processing, Medical,Image Processings, Medical,Image Reconstructions,Medical Image Processings,Processing, Biomedical Image,Processing, Digital Image,Processing, Medical Image,Processings, Digital Image,Processings, Medical Image,Reconstruction, Image,Reconstructions, Image
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000465 Algorithms A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task. Algorithm
D014057 Tomography, X-Ray Computed Tomography using x-ray transmission and a computer algorithm to reconstruct the image. CAT Scan, X-Ray,CT Scan, X-Ray,Cine-CT,Computerized Tomography, X-Ray,Electron Beam Computed Tomography,Tomodensitometry,Tomography, Transmission Computed,X-Ray Tomography, Computed,CAT Scan, X Ray,CT X Ray,Computed Tomography, X-Ray,Computed X Ray Tomography,Computerized Tomography, X Ray,Electron Beam Tomography,Tomography, X Ray Computed,Tomography, X-Ray Computer Assisted,Tomography, X-Ray Computerized,Tomography, X-Ray Computerized Axial,Tomography, Xray Computed,X Ray Computerized Tomography,X Ray Tomography, Computed,X-Ray Computer Assisted Tomography,X-Ray Computerized Axial Tomography,Beam Tomography, Electron,CAT Scans, X-Ray,CT Scan, X Ray,CT Scans, X-Ray,CT X Rays,Cine CT,Computed Tomography, Transmission,Computed Tomography, X Ray,Computed Tomography, Xray,Computed X-Ray Tomography,Scan, X-Ray CAT,Scan, X-Ray CT,Scans, X-Ray CAT,Scans, X-Ray CT,Tomographies, Computed X-Ray,Tomography, Computed X-Ray,Tomography, Electron Beam,Tomography, X Ray Computer Assisted,Tomography, X Ray Computerized,Tomography, X Ray Computerized Axial,Transmission Computed Tomography,X Ray Computer Assisted Tomography,X Ray Computerized Axial Tomography,X Ray, CT,X Rays, CT,X-Ray CAT Scan,X-Ray CAT Scans,X-Ray CT Scan,X-Ray CT Scans,X-Ray Computed Tomography,X-Ray Computerized Tomography,Xray Computed Tomography
D015233 Models, Statistical Statistical formulations or analyses which, when applied to data and found to fit the data, are then used to verify the assumptions and parameters used in the analysis. Examples of statistical models are the linear model, binomial model, polynomial model, two-parameter model, etc. Probabilistic Models,Statistical Models,Two-Parameter Models,Model, Statistical,Models, Binomial,Models, Polynomial,Statistical Model,Binomial Model,Binomial Models,Model, Binomial,Model, Polynomial,Model, Probabilistic,Model, Two-Parameter,Models, Probabilistic,Models, Two-Parameter,Polynomial Model,Polynomial Models,Probabilistic Model,Two Parameter Models,Two-Parameter Model
D017785 Photons Discrete concentrations of energy, apparently massless elementary particles, that move at the speed of light. They are the unit or quantum of electromagnetic radiation. Photons are emitted when electrons move from one energy state to another. (From Hawley's Condensed Chemical Dictionary, 11th ed)
D019047 Phantoms, Imaging Devices or objects in various imaging techniques used to visualize or enhance visualization by simulating conditions encountered in the procedure. Phantoms are used very often in procedures employing or measuring x-irradiation or radioactive material to evaluate performance. Phantoms often have properties similar to human tissue. Water demonstrates absorbing properties similar to normal tissue, hence water-filled phantoms are used to map radiation levels. Phantoms are used also as teaching aids to simulate real conditions with x-ray or ultrasonic machines. (From Iturralde, Dictionary and Handbook of Nuclear Medicine and Clinical Imaging, 1990) Phantoms, Radiographic,Phantoms, Radiologic,Radiographic Phantoms,Radiologic Phantoms,Phantom, Radiographic,Phantom, Radiologic,Radiographic Phantom,Radiologic Phantom,Imaging Phantom,Imaging Phantoms,Phantom, Imaging
D019277 Entropy The measure of that part of the heat or energy of a system which is not available to perform work. Entropy increases in all natural (spontaneous and irreversible) processes. (From Dorland, 28th ed) Entropies

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