ECAT - NEW COMPUTERIZED TOMOGRAPHIC IMAGING-SYSTEM FOR POSITRON-EMITTING RADIOPHARMACEUTICALS

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  • 1 January 1978
    • journal article
    • research article
    • Vol. 19  (6) , 635-647
Abstract
The ECT [emission computerized tomography] was designed and developed as a positron imaging system capable of providing high contrast, high resolution, quantitative images in 2-dimensional (2-D) and tomographic formats. The flexibility in its various image mode options makes it useful for a wide variety of imaging problems. High (HR), medium (MR) and low (LR) tomographic resolutions were 0.95 .+-. 0.1, 1.3 .+-. 0.1 and 1.7 .+-. 0.1 cm FWHM [full width half maximum], high, medium and low resolutions in 2-D images were 0.85 .+-. 0.1, 1.3 .+-. 0.1 and 1.7 .+-. 0.1, depending on resolution mode employed. ECT system efficiency is 30,100, 15,900 and 9200 counts/s per .mu.Ci per ml with a 20-cm diameter phantom at LR, MR and HR. Because of the geometric, detector, electronic and shielding design of the system, count-rate capability and linearity were high, with minimum detection of scattered radiation and random coincidence. Measured error agrees well with theoretical statistical predictions down to a level of 1.4% standard deviation. The redundant sampling scheme of this system significantly reduces errors caused by motion and detector instability. Scan times are variable from 10 s to several min/slice and multiple levels were automatically performed by computer control of patient bed. A variety of human studies illustrate image quality, resolution and efficiency of both ECT and 2-D imaging mode. Examples of the noninvasive study method were made possible through development of ECT.