An In Vivo Bone Densitometer for use with a Diagnostic X-Ray Set

  • John P.N. Edwards

    Student thesis: Doctoral ThesisDoctor of Philosophy


    An invivo bone densitometer has been designed to be used
    with a full wave rectified X ray set. The densitometer has been
    constructed to give a fast and accurate scan of the ulna with a
    spatial resolution very much better than hitherto achieved.

    The ulna was chosen so that a wide range of patients, who
    might have limited agility could be easily scammed for bone
    mineral content with a view to the early diagnosis of bone
    disease and to study progress and response to therapy.

    To overcome the X ray output fluctuations due to variations
    of the supply voltage, an electronic compensation technique
    using two detectors was developed. One of the detectors samples
    the total incident X ray intensity over a portion of the every
    half cycle, and the other the X ray intensity transmitted
    through the ulna.

    Tests to determine the performance of the compensation
    mechanism over a wide range of operating conditions were made,
    The reproducibility of the densitometer has been demonstrated
    by making scans using simulated dead and invivo bone.

    Theoretical calculations using a simplified theory have Been
    made to predict the accuracy of the compensation technique and
    the expected voltage signals. These calculations are compared
    with experimental observation.
    Date of Award1973
    Original languageEnglish


    • in vivo
    • bone densitometer
    • diagnostic
    • x-ray

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