Control Means for Heat Load in X-Ray Scanning Apparatus

Abstract

The present invention is an X-ray scanning system having at least one multi-focus X-ray tubes spaced around an axis and arranged to emit X-rays through an object on the axis. The emitted X-rays are detected by sensors. Each multi-focus X-ray tube can emit X-rays from a plurality of source positions. In an exemplary scanning cycle, each of the source positions in each X-ray tube is used at least once and ordered to minimize the thermal load on the tubes.

1 - 13 . (canceled) 
     
     
         14 . An X-ray imaging apparatus comprising:
 at least one X-ray tube comprising a first X-ray source and a second X-ray source, wherein each of said first and second X-ray sources produce X-rays and wherein the first X-ray source and the second X-ray source are adjacent each other and spaced from each other by a first spacing;   at least one X-ray sensor to detect X-rays emitted from the at least one X-ray tube; and   a controller for activating said first X-ray source when said second X-ray source is inactive and for activating said second X-ray source when said first X-ray source is inactive.   
     
     
         15 . The X-ray imaging apparatus of claim  1  wherein said X-ray tube comprises a third X-ray source and wherein said third X-ray source is spaced from said first X-ray source by a second spacing. 
     
     
         16 . The X-ray imaging apparatus of  claim 15  wherein said second spacing is greater than said first spacing. 
     
     
         17 . The X-ray imaging apparatus of  claim 16  wherein said controller first activates said first X-ray source while keeping inactive the second X-ray source and the third X-ray source. 
     
     
         18 . The X-ray imaging apparatus of  claim 17  wherein said controller activates said third X-ray source, while keeping inactive the first and second X-ray sources, immediately after inactivating said first X-ray source. 
     
     
         19 . The X-ray imaging apparatus of  claim 14  further comprising a second X-ray tube comprising a first X-ray source and a second X-ray source, wherein each of said first and second X-ray sources produce X-rays and wherein the first X-ray source and the second X-ray source are adjacent each other and spaced from each other by a spacing; 
     
     
         20 . The X-ray imaging apparatus of  claim 19  wherein the controller immediately activates the first X-ray source in the second X-ray tube after inactivating the first X-ray source in the at least one X-ray tube and before activating the second X-ray source in the at least one X-ray tube. 
     
     
         21 . An X-ray imaging apparatus comprising
 a first X-ray tube comprising a first plurality of source positions, including a first source position and a second source position, wherein the first source position and the second source position are adjacent each other and spaced from each other by a first source spacing;   a second X-ray tube comprising a second plurality of source positions, including a third source position and a fourth source position, wherein the third source position and the fourth source position are adjacent each other and spaced from each other by a second source spacing;   at least one X-ray sensor to detect X-rays emitted from the first or second X-ray tubes; and   a controller for controlling an order in which the first, second, third, and fourth source positions are active such that a displacement between an active source position in one emission period and an active source position in a period immediately after the emission period is greater than an amount related to said first and second source spacing.   
     
     
         22 . The imaging apparatus of  claim 21  wherein said displacement is at least twice the first source spacing. 
     
     
         23 . The imaging apparatus of  claim 21  wherein said displacement is at least twice the second source spacing. 
     
     
         24 . The imaging apparatus of  claim 21  wherein an active source position in the emission period is not adjacent a source position that is active in the period immediately after the emission period. 
     
     
         25 . The imaging apparatus of  claim 21  wherein only one of the first, second, third or fourth source position in an X-ray tube is active in each emission period. 
     
     
         26 . The imaging apparatus of  claim 21  wherein one source in said first X-ray tube and one source in said second X-ray tube are active simultaneously in each emission period. 
     
     
         27 . The imaging apparatus of  claim 21  wherein, in each emission period, more than one source position is active and each of said active source positions is located in a different X-ray tube. 
     
     
         28 . The imaging apparatus of  claim 21  wherein only one source position in each X-ray tube is active in each emission period and each X-ray tube is active in a sequential order.