Patent Document ID: 4105922
Application ID: 05786528
Patent Status: 1

Claim One:
1. In a computed tomography system including means for producing first electric signals having a large range of values corresponding respectively with the X-ray attenuation and CT numbers of volume elements in a layer of a body; a memory matrix for storing said signals; display means for displaying a visual image depending on said stored signals comprising an intensity modulatable scanning cathode ray tube and means for modulating the intensity of said tube in correspondence with the values of successive signals; means for selecting from said large range of signal values signals lying within a window comprised of a smaller range of values defined by upper and lower limits and a level value centered between said limits; means for converting said signals within said window to signals for modulating said cathode ray tube; and, improved means for identifying the CT numbers corresponding with selected zones in said displayed image comprising: means for selecting signals in a narrow band corresponding substantially with the CT number values of said level within the selected window; means for activating said selecting means; and means for causing said selected signals to modulate only those zones in said displayed image which have CT numbers corresponding substantially with said selected level to an intensity corresponding with said level and alternately in quick succession to higher intensity whereby to enable identification of the CT numbers.