• Login
    View Item 
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Dissertations
    • View Item
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of UA Campus RepositoryCommunitiesTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournalThis CollectionTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournal

    My Account

    LoginRegister

    About

    AboutUA Faculty PublicationsUA DissertationsUA Master's ThesesUA Honors ThesesUA PressUA YearbooksUA CatalogsUA Libraries

    Statistics

    Most Popular ItemsStatistics by CountryMost Popular Authors

    Modular gamma cameras: Improvements in scatter rejection, and characterization and initial clinical application.

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    azu_td_9534674_sip1_c.pdf
    Size:
    44.00Mb
    Format:
    PDF
    Download
    Author
    Chen, Jyhcheng.
    Issue Date
    1995
    Committee Chair
    Barrett, Harrison H.
    
    Metadata
    Show full item record
    Publisher
    The University of Arizona.
    Rights
    Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
    Abstract
    This dissertation reports investigations into improvements of the performance of "modular" gamma-ray cameras. Each modular camera has a 10 cm x 10 cm NaI(Tl) scintillation crystal and four 5 cm x 5 cm photomultiplier tubes (PMTs). When the gamma-ray photons interact with the crystal, scintillation flashes are emitted from the crystal and detected by the PMTs. The PMTs then convert the light flashes to current pulses. A digital computing circuitry processes the PMT outputs and assigns an estimated (x,y) coordinate corresponding to the location of interaction of each gamma-ray photon in the crystal and thus an image is formed. This dissertation is concerned with improvements and clinical applications of the modular cameras. There are some areas in which we improve the camera performance. These areas include position and energy estimation, and scatter rejection. We use look-up tables (LUTs) with different windowing methods to estimate the scintillation positions and reject scattered photons. We study several possible position estimators and compare the results by the bias and the variance of the position estimates. There are two types of events that occur in our image: photoelectric absorption and Compton scattering. When gamma rays are emitted from the organ, scattered photons will be generated which are not the desired events. Milster et al. introduced a discrimination method called the likelihood window (LW) to reject scattered events. We also extend the maximum-likelihood estimation rule to include energy estimation of different gamma-ray photons. Then we use the LUTs calculated from both position and energy estimators to study scatter rejection by the energy window (EW) when there are scattered photons. We introduce a Bayesian window (BW) for scatter rejection and compare the results with our usual LW and EW through receiver operating characteristic studies. We measure the short-term and long-term stability of PMT gain. We describe and compare some uniformity correction methods used in the research group. We do the camera characterization by measuring spatial resolution and sensitivity of the modular camera and compare these characteristics to those of the commercial gamma camera. We design and construct a stand-alone planar imaging system based on the modular camera. This imager is examined with a set of phantom and clinical tests to demonstrate the clinical feasibility of the stand-alone system.
    Type
    text
    Dissertation-Reproduction (electronic)
    Degree Name
    Ph.D.
    Degree Level
    doctoral
    Degree Program
    Optical Sciences
    Graduate College
    Degree Grantor
    University of Arizona
    Collections
    Dissertations

    entitlement

     
    The University of Arizona Libraries | 1510 E. University Blvd. | Tucson, AZ 85721-0055
    Tel 520-621-6442 | repository@u.library.arizona.edu
    DSpace software copyright © 2002-2017  DuraSpace
    Quick Guide | Contact Us | Send Feedback
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.