STP716: Computerized Fluorodensitometry Using a Solid-State Matrix Camera

    Ziskin, MC
    Professor of Radiology and Medical Physics and assistant professor of Medical Physics, Temple University Medical School, Philadelphia, Pa.

    Philips, CM
    Professor of Radiology and Medical Physics and assistant professor of Medical Physics, Temple University Medical School, Philadelphia, Pa.

    Pages: 9    Published: Jan 1980


    Abstract

    Conventional televised fluoroscopy enables real-time visualization of dynamically changing structures within the body provided there is adequate radiologic contrast between the object of interest and its immediate surround. Under special conditions, such as in arteriography, injection of a contrast agent into the structure being studied enhances its visualization. Where applicable, greatest contrast enhancement is provided by image subtraction. In our experience, because of the intrinsic noisiness of television (TV), radiologic contrast had to exceed 5 percent for visualization by any of the aforementioned techniques.

    In order to measure a 1 percent X-ray transmission variation, we have replaced the vidicon camera with a Reticon solid-state matrix camera. This camera contains a 32 by 32 photodiode array with an intrinsic noise level far below that of standard TV. However, a fixed-pattern pixel noise due to differing pixel sensitivities must be canceled out. This is easily performed by subtraction with a dark-field pixel pattern previously stored in a computer. The frame rate of the camera can be varied from 15 to 100 Hz.

    The video signal is digitized and entered into a LINC-8 digital computer for densitometry. The primary use of this system to date has been in the measurement of pulmonary pulsations in monkeys. These pulmonary pulsations are small variations in X-ray transmission through the chest due to the change in blood content of the lungs during each heartbeat. A decrease in the amplitude of pulmonary pulsations is a potentially important diagnostic sign in the clinical evaluation of cardiac failure and in early lung cancer.

    Keywords:

    fluorodensitometry, videodensitometry, solid-state camera, computerized fluoroscopy


    Paper ID: STP27514S

    Committee/Subcommittee: E07.01

    DOI: 10.1520/STP27514S


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