Patent Abstract:
a device and a method for calibrating the coordinate system of imaging systems having a tracking system prior or during image data acquisition , e . g . by way of magnetic resonance tomography .

Detailed Description:
the reference numerals of corresponding elements in the figures are identical . in accordance with fig1 , the schematically illustrated device 1 comprises a tracking system 10 which is arranged in an imaging system 20 e . g . for mrt . the tracking system 10 has a coordinate system 50 . the device moreover has a first marker 70 which is stationary relative to the imaging system 20 as a reference marker and the position and orientation of which are calibrated in a coordinate system 60 of the imaging system 20 . the tracking system 10 and the first marker 70 are arranged within the imaging system 20 . a second marker 30 is provided on a movable object 40 such that the position and orientation of the marker 30 can be detected in the coordinate system 50 of the tracking system 10 during imaging and can be transferred to the coordinate system 60 of the imaging system 20 . in principle , the device 1 for calibrating tracking systems 10 in imaging systems 20 a , 20 b , 20 c , e . g . for mrt or imrt or ct , may comprise at least the following components : a tracking system 10 with a coordinate system 50 , at least one imaging system 20 a , 20 b , 20 c , and at least one first marker 70 a , 70 b , 70 c that is arranged stationarily relative to the imaging system 20 a , 20 b , 20 c as a reference marker , and the position and orientation of which are calibrated in a coordinate system 60 a , 60 b , 60 c of the imaging system 20 a , 20 b , 20 c as is also illustrated below in fig2 a - 2 c . fig2 a , 2 b and 2 c schematically show an arrangement of several imaging systems with associated coordinate systems analogous to fig1 , wherein in fig2 a , 2 b and 2 c , the same object 40 is examined in each case with a first marker 70 a , 70 b , 70 c in different imaging or therapy modalities 20 a , 20 b , 20 c . in accordance therewith , each of a plurality of markers 70 a , 70 b , 70 c is arranged in imaging systems 20 a e . g . for mrt , 20 b e . g . for ct , and 20 c e . g . for imrt but also pet such that their positions and orientations in the coordinate systems 60 a , 60 b , 60 c of the respective imaging system 20 a , 20 b , 20 c have been calibrated , wherein the position and orientation of the object marker 30 can be transferred from the coordinate system 60 a of the imaging system 20 a to the coordinate systems 60 b and / or 60 c of the imaging systems 20 b and / or 20 c . the second marker 30 is advantageously mounted for arrangement on the movable object 40 such that the position and orientation of the marker 30 in the coordinate system 50 of the tracking system 10 can be detected during imaging and can be transferred to or be converted into the coordinate system 60 a , 60 b , 60 c of the imaging system 20 a , 20 b , 20 c . the first marker 70 a , 70 b , 70 c thereby cooperates with the tracking system 10 in such a fashion that a changing position of the tracking system 10 during imaging can be detected via the tracking system 10 by means of the first marker 70 a , 70 b , 70 c and the tracking system 10 can be re - calibrated . the tracking system 10 can thereby be arranged within or outside of the imaging system 20 a , 20 b , 20 c . the first marker 70 a , 70 b , 70 c can also be arranged within or outside of the imaging system 20 a , 20 b , 20 c . each of a plurality of markers 70 a , 70 b , 70 c are arranged in respective imaging systems 20 a , 20 b , 20 c such that their positions and orientations in the coordinate system 60 a , 60 b , 60 c of the respective imaging system 20 a , 20 b , 20 c are calibrated , wherein the position and orientation of the marker 30 arranged on the movable object 40 can be converted from the coordinate system 60 a of the imaging system 20 a into the coordinate systems 60 b , 60 c of the imaging systems 20 b , 20 c . in each case , the imaging modality is naturally a different one , e . g . mrt , ct , imrt , pet , spect and the like , wherein the reference marker is a different one in each case , since it is permanently connected to the imaging device . the tracking system may also be a different one or the same and be mobile or be stationary within or outside of the imaging system . 1 ) thesen s , heid o , mueller e , schad l r . prospective acquisition correction for head motion with image - based tracking for real - time fmri . magn reson med 2000 ; 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