Adjustable dual-detector image data acquisition system

Abstract

An improved image acquisition system allows the angular displacement between two detectors to be adjusted between 90° and 180° to reduce the imaging time for both 360° and 180° scans. A patient table is displaced vertically and horizontally from a lateral axis to allow the body of a patient to be positioned next to the detectors and to improve resolution.

What is claimed is:  
     
       1. An imaging system for acquiring imaging data generated by an object positioned about a lateral axis to form a SPECT image, said system comprising: 
       first and second gamma ray detectors;  
       a first pair of rings, oriented substantially perpendicular to and approximately centered on the lateral axis;  
       means for coupling said first detector to said first pair of rings, with the first detector pointed toward the lateral axis and disposed between said rings;  
       an arc shaped groove in each of said first pair of rings being substantially parallel to a circumference of the rings;  
       means for coupling said second detector to said arc shaped groove; and  
       means for moving said second detector along said arc shaped groove to vary the angular displacement, relative to the lateral axis, between said first and second detectors to predetermined magnitude.  
     
     
       2. An imaging system for acquiring imaging data generated by an object positioned about a lateral axis, said system comprising: 
       first and second detectors each having a collimator surface oriented perpendicularly to the direction said detectors are pointing;  
       a first ring oriented substantially perpendicular to and approximately centered on the lateral axis;  
       a first cantilever support coupled to said ring having said first detector mounted thereon;  
       an arc shaped groove on said ring said groove being substantially parallel to the circumference of said ring;  
       a second cantilever support having said second detector mounted thereon;  
       one or more guide rollers rotatably attached to said second cantilever support and engaged to said groove;  
       a shaft rotatably attached to said second cantilever support;  
       a gear fixedly attached to said shaft and engaged to said ring;  
       a motor controllingly coupled to said shaft, whereby the operation of said motor by moving said second cantilever support along said groove varies the orientation, relative to the lateral axis and in said plane, of the collimator surfaces of said first and second detectors between a first position where said collimator surfaces are parallel and a second position where said collimator surfaces are perpendicular.  
     
     
       3. The system of claim  2  further comprising: 
       a radial motion mechanism coupling said first cantilever support to said first ring said radial motion mechanism comprising  
       a first base plate attached to said first ring;  
       a first slotted guide bar fixedly attached to said first base plate;  
       one or more guide rollers rotatably attached to said first cantilever support and engaged to said first slotted guide bar;  
       a swivel nut attached to said first cantilever support through a bracket;  
       a first lead screw rotatably coupled to said swivel nut, said first lead screw rotatably mounted in a plurality of bearing blocks, said bearing blocks fixedly attached to said first base plate;  
       a trailer gear fixedly attached to said first lead screw;  
       a coupling gear fixedly attached to said first lead screw;  
       a lead drive gear controllingly coupled to said trailer gear through a coupling chain;  
       a drive motor controlling by coupled to said lead drive gear;  
       whereby through the action of said drive motor said first detector may be moved toward and away from the lateral axes.  
     
     
       4. The system of claim  3  further comprising: 
       a second ring substantially parallel to said first ring with said detectors lying between said rings;  
       a third cantilever support coupling said first detector to said second ring;  
       a second radial motion mechanism coupling said third cantilever support to said second ring, said second radial motion mechanism comprising  
       a second base plate fixedly attached to said second ring;  
       a second slotted guide bar fixedly attached to said second base plate;  
       one or more guide rollers rotatably attached to said third cantilever support and engaged to said second slotted guide bar;  
       a swivel nut fixedly attached to said first cantilever support;  
       a second lead screw rotatably coupled to said swivel nut, said second lead screw rotatably mounted in a plurality of bearing blocks, said bearing blocks fixedly attached to said second base plate;  
       a coupling gear fixedly attached to said second lead screw;  
       a coupling chain coupling said coupling gear of said first radial motion mechanism and said coupling gear of said second radial motion mechanism;  
       whereby said first radial motion mechanism and said second radial motion mechanism may be operated in tandem to move said first detector toward and away from the lateral axis.  
     
     
       5. The system of claim  2  further comprising 
       a radial motion mechanism coupling said second cantilever support to said first ring said radial motion mechanism comprising  
       a first base plate attached to said first ring;  
       a first slotted guide bar fixedly attached to said first base plate;  
       one or more guide rollers rotatably attached to said second cantilever support and engaged to said first slotted guide bar;  
       a swivel nut attached to said first cantilever support through a bracket;  
       a first lead screw rotatably coupled to said swivel nut, said first lead screw rotatably mounted in a plurality of bearing blocks, said bearing blocks fixedly attached to said first base plate;  
       a trailer gear fixedly attached to said first lead screw;  
       a coupling gear fixedly attached to said first lead screw;  
       a lead drive gear controllingly coupled to said trailer gear through a coupling chain;  
       a drive motor controlling by coupled to said lead drive gear;  
       whereby through the action of said drive motor said second detector may be moved toward and away from the lateral axis.  
     
     
       6. The system of claim  5  further comprising: 
       a second ring substantially parallel to said first ring with said detectors lying between said rings;  
       a third cantilever support coupling said second detector to said second ring;  
       a second radial motion mechanism coupling said third cantilever support to said second ring said radial motion mechanism comprising  
       a second base plate fixedly attached to said second ring;  
       a second slotted guide bar fixedly attached to said second base plate;  
       one or more guide rollers rotatably attached to said third cantilever support and engaged to said second slotted guide bar;  
       a swivel nut fixedly attached to said first cantilever support;  
       a second lead screw rotatably coupled to said swivel nut, said second lead screw rotatably mounted in a plurality of bearing blocks, said bearing blocks fixedly attached to said second base plate;  
       a coupling gear fixedly attached to said second lead screw;  
       a coupling chain coupling said coupling gear of said first radial motion mechanism and said coupling gear of said second radial motion mechanism;  
       whereby said first radial motion mechanism and said second radial motion mechanism may be operated in tandem to move said second detector toward and away from the lateral axis.  
     
     
       7. An imaging system for acquiring imaging data generated by an object positioned about a lateral axis to form a SPECT image, said system comprising: 
       a main gantry body having left and right upright cylindrical walls each having an inner surface and an outer surface, said walls including a plurality of guide rollers rotatably attached to the inner surface of the walls at spaced apart radial positions;  
       first and second gamma ray detectors;  
       a first pair of rings located between said walls and oriented substantially perpendicular to and approximately centered on the lateral axis, each of said first pair of rings including a main cylindrical body having an inner face and an outer face, an outer radial flange integral with and perpendicular to an upper portion of said outer face and disposed towards and adjacent said gantry walls, and an L-shaped inner flange having a first member defining an upper radial support surface, said first member being integral with and perpendicular to a middle portion of said inner face, said L-shaped flange having a second member integral with and perpendicular to said first member and having one end proximate said lateral axis and having an integral upper lip extending above said radial support surface at the opposite end of the second member, wherein said outer flange defines a radial abutment undersurface for engaging said rollers attached to said walls of the main gantry body, and wherein said second member of said L-shaped inner flange and said inner face of said main cylindrical body define an inner radial groove therebetween;  
       a second pair of rings located between said walls and oriented substantially perpendicular to and approximately centered on the lateral axis, each of said second pair of rings having an inner face, an outer face, a side wall face, and a radial groove formed in the side wall face between the inner and outer face, wherein each of said rings includes a plurality of guide rollers rotatably mounted within the groove and extending slightly beyond said groove, said rollers radially spaced apart from each other around an inner surface of the groove for positioning each of said second rings upon said upper radial support surface of said first member of said L-shaped inner flange of each of said first pair of rings so that said second pair of rings is disposed between said first pair of rings and is rotatable along said radial support surface and is prevented from falling off of said surface by said upper lip of the second member of the L-shaped flange;  
       means for coupling said first and second detectors to said first and second pairs of rings respectively, with the first and second detectors pointed toward the lateral axis and disposed between said rings, said coupling means including means for moving the first and second detectors respectively toward and away from the lateral axis; and  
       means for independently rotating said first and second detectors along a circular path approximately centered at said lateral axis.  
     
     
       8. An imaging system as claimed in claim  7  wherein said independent by rotating means includes a motor operatively coupled to first and second drive shafts, a pair of first and second drive gears fixedly attached to said first and second shafts, at least one pair of first and second idler gears operatively coupling said first and second drive gears to said first and second pairs of rings, and a braking means coupled to said second drive shaft; 
       wherein when said braking means is disengaged, the operation of the motor rotates said first and second shafts to thereby rotate said drive gears, said idler gears, and said rings and said detectors coupled thereto in a circular path approximately centered on the lateral axis, and wherein when said braking means is engaged, operation of said motor rotates only said first shaft so that rotation occurs only for said first gears and said first pair of rings to thereby adjust the angular displacement, relative to the lateral axis, between said first and second detectors to a predetermined magnitude.  
     
     
       9. An imaging system as claimed in claim  7  further comprising a plurality of adjustment blocks movably mounted to said gantry body walls and spaced radially apart from each other, each of said blocks having a guide roller rotatably fixed to the block and adapted to be positioned within the inner radial groove of said first pair of rings, wherein said adjustment blocks may be moved axially within said gantry walls substantially parallel to said lateral axis to thereby vary a lateral displacement of said first pair of rings from said gantry walls. 
     
     
       10. A medical imaging system for acquiring image data of an object, said system comprising: 
       
         a first pair of rotatable members rotatable about and substantially centered on a lateral axis;  
       
       
         a second pair of rotatable members rotatable about and substantially centered on a lateral axis;  
       
       
         a first radiation detector coupled to and disposed between the first pair of rotatable members; and  
       
       
         a second radiation detector coupled to and disposed between the second pair of rotatable members, the second pair of rotatable members movable with respect to the first pair of rotatable members so as to allow the angular displacement between the first and second detectors about the lateral axis to be varied. 
       
     
     
       11. A medical imaging system according to claim  10 , wherein the first and second detectors are gamma radiation detectors. 
     
     
       12. A medical imaging system according to claim  10 , wherein the first pair of rotatable members comprises a pair of ring- shaped members including a first ring - shaped member and a second ring - shaped member, and wherein the second pair of rotatable members comprises a pair of ring - shaped members including a third ring - shaped member and a fourth ring - shaped member.   
     
     
       13. A medical imaging system according to claim  10 , wherein the second pair of rotatable members is disposed between the first pair of rotatable members. 
     
     
       14. An imaging system according to claim  10 , wherein the angular displacement can be substantially any angle in a range from less than  90  degrees to approximately  180  degrees. 
     
     
       15. An imaging system according to claim  10 , wherein each of the first and second radiation detectors includes a substantially planar surface, and wherein the imaging system further comprises first and second extended collimators mounted to the first and second radiation detectors, respectively, each of the first and second extended collimators having a collimator surface extending substantially beyond the planar surface of the corresponding detector. 
     
     
       16. An imaging system according to claim  15 , wherein each of the first and second detectors comprises a beveled edge for reducing mechanical interference between the first and second detectors when the first and second detectors are oriented substantially perpendicular to each other. 
     
     
       17. An imaging system according to claim  10 , further comprising: 
       
         means for rotating the first and second radiation detectors through a circular path centered substantially about the lateral axis to a plurality of angular positions to acquire the image data; and  
       
       
         means for varying the relative position of the object with respect to the first and second radiation detectors, vertically and horizontally with respect to the lateral axis, to substantially minimize the distance between the object and the first and second gamma ray detectors at each of the plurality of angular positions. 
       
     
     
       18. A medical imaging system for acquiring tomographic image data of an object, said system comprising: 
       
         a first pair of ring members rotatable about and substantially centered on a lateral axis;  
       
       
         a second pair of ring members rotatable about and substantially centered on a lateral axis and disposed between the first pair of ring members;  
       
       
         a first gamma ray detector coupled to and disposed between the first pair of ring members; and  
       
       
         a second gamma ray detector coupled to and disposed between the second pair of ring members, the second pair of ring members rotatable with respect to the first pair of ring members so as to allow the angular displacement between the first and second gamma ray detectors about the lateral axis to be varied. 
       
     
     
       19. An imaging system according to claim  18 , wherein the angular displacement can be substantially any angle in a range from less than  90  degrees to approximately  180  degrees. 
     
     
       20. An imaging system according to claim  18 , wherein each of the first and second gamma ray detectors includes a substantially planar surface, and wherein the medical imaging system further comprises first and second extended collimators mounted to the first and second gamma ray detectors, respectively, each of the first and second extended collimators having a collimator surface extending substantially beyond the planar surface of the corresponding detector. 
     
     
       21. A medical imaging system according to claim  18 , wherein each of the first and second gamma ray detectors comprises a beveled edge for reducing mechanical interference between the first and second gamma ray detectors when the first and second gamma ray detectors are oriented substantially perpendicular to each other. 
     
     
       22. An imaging system according to claim  18 , further comprising: 
       
         means for rotating the first and second gamma ray detectors through a circular path centered substantially about the lateral axis to a plurality of angular positions to acquire the image data; and  
       
       
         means for varying the relative position of the object with respect to the first and second gamma ray detectors, vertically and horizontally with respect to the lateral axis, to substantially minimize the distance between the object and the first and second gamma ray detectors at each of the plurality of angular positions.