| 摘要 |
An axial tomography system is disclosed which includes an assembly rotatable about an axis extending along a central opening defined therein, and means for positioning the body portion to be examined within the central opening so that the axis of assembly rotation is perpendicular to a plane passing through the bodily structures to be examined. A source of penetrating radiation is mounted on the assembly toward one side thereof and via a first collimating means provides radiation in the form of a fan beam. The first collimating means is mounted proximate to the radiation source, and includes an adjustable slit, which can be opened completely to enable a conventional x-ray exposure. Means are provided for rotating the assembly so that the fan beam impinges upon said body portion at a plurality of incident directions. Detector means for the radiation are positioned on the assembly opposite the source, enabling detection of radiation which traverses laterally and is not absorbed in the thin body section in which the aforementioned plane resides. The detector means is preferably of the ionization type, and may comprise an array of side-by-side cells. Second collimating means including a series of parallel plates overlie the detector means and assure that the radiation incident on each cell is substantially only that which has propagated along the radius of the fan beam which joins the cell to the radiation source. A third collimating means directly overlies the second, and comprises a slit extending transversely to the aforementioned plates.
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