Method and magnetic resonance apparatus for synchronous imaging and radiation therapy

Abstract

In a method for synchronous magnetic resonance (MR) imaging and radiation therapy using a combined system having a radiation apparatus and an MR imaging apparatus, wherein the system is designed to record MR signals of a subject during irradiation of the subject, a three-dimensional MR volume data set of the subject is acquired that contains a target volume for the irradiation, the location of a central beam of the radiation therapy apparatus relative to the subject, is continuously determined, and a second MR image data set is determined, which is positioned essentially perpendicular to the central beam. If the location of the central beam changes, a correspondingly changed second MR image data set is determined perpendicular to the central beam.

1 . A method for controlling a combined system comprising a radiation therapy apparatus and a magnetic resonance (MR) imaging apparatus, said method comprising:
 from a control computer, operating the combined system to acquire MR signals from a subject during irradiation of the subject with a radiation beam having a central beam;   operating said MR imaging apparatus to acquire a three-dimensional MR volume data set that contains a target volume for irradiation with said radiation beam;   in said control computer, continuously determining a location of the central beam relative to the subject;   in said computer, determining a further MR image data set that is positioned substantially perpendicularly to central beam and, if the location of the central beam changes, acquiring a changed second MR data set that is substantially perpendicular to the central beam; and   from said control computer, emitting a control signal, dependent on said changed further MR data set, to said radiation therapy apparatus that changes said radiation beam.   
     
     
         2 . The method as claimed in  claim 1 , wherein the changed second MR image data set is an MR image data set which is recorded in a volume during the irradiation of the subject, and wherein, if the location of the central beam changes, acquiring the changed MR image data set such that a changed volume of the MR image data set lies perpendicular to the central beam. 
     
     
         3 . The method as claimed in  claim 1 , comprising acquiring the second MR image data set is determined so as to at least partly contain the target volume. 
     
     
         4 . The method as claimed in  claim 1 , comprising acquiring the three-dimensional MR volume data set of the subject is recorded prior to the irradiation. 
     
     
         5 . The method as claimed in  claim 1 , comprising calculating a transformation from a comparison between the three-dimensional MR volume data set and the second MR image data set, said transformation describing the movement between the recording of the MR volume data set and the determination of the second image data set, and calculating a deformed three-dimensional MR volume data set by applying the transformation to the MR volume data set. 
     
     
         6 . The method as claimed in  claim 5 , comprising in the event of a changed location of the central beam, calculating each of a transformation and a deformed MR volume data set. 
     
     
         7 . The method as claimed in  claim 1 , comprising determining a position of an organ in the subject, and acquiring the second image data set such that the organ is contained at least partly in the second image data set. 
     
     
         8 . The method as claimed in  claim 1 , wherein the changed second MR image data set is an MR image data set which is recorded in a volume during the irradiation of the subject, and wherein, if the location of the central beam changes, acquiring the changed MR image data set such that a changed volume of the MR image data set lies perpendicular to the central beam, and acquiring the MR image data set and the changed MR volume data set in a plurality of two-dimensional slices which lie perpendicular to the central beam. 
     
     
         9 . The method as  claim 1 , comprising using the second MR image data set to determine a radiation dose for the irradiation in predetermined regions of the subject. 
     
     
         10 . The method as claimed in  claim 9 , comprising using the determined radiation dose to control the irradiation, and switch off the irradiation automatically if a limit dose is exceeded in defined anatomical regions of the subject. 
     
     
         11 . The method as claimed in  claim 1 , comprising determining the location of the central beam using control data, with which the location of the central beam is controlled by the radiation therapy apparatus. 
     
     
         12 . The method as claimed in  claim 1 , comprising determining the location of the central beam using image data acquired by a camera during recording of the central beam. 
     
     
         13 . The method as claimed in  claim 1 , comprising determining the location of the central beam using defined markings which occupy a defined location relative to the central beam in MR image data. 
     
     
         14 . The method as claimed in  claim 1  comprising acquiring the second MR image data set is determined so as to at least partly contain the target volume, and comprising determining movement information of the subject, and using the movement information and the dimensional MR volume data set to calculate the second MR image data set. 
     
     
         15 . The method as claimed in  claim 14 , comprising calculating a transformation from a comparison between the three-dimensional MR volume data set and the second MR image data set, said transformation describing the movement between the recording of the MR volume data set and the determination of the second image data set, and calculating a deformed three-dimensional MR volume data set by applying the transformation to the MR volume data set, and comprising calculating the transformation from the three-dimensional MR volume data set and the movement information, and calculating a deformed second MR image data set is calculated from the second MR image data set and the deformation. 
     
     
         16 . The method as claimed in  claim 15 , wherein the deformed second MR image data set contains a plurality of two-dimensional slices, and calculating the deformed three-dimensional volume data set is calculated using the deformed second MR image data set and the three-dimensional MR volume data set. 
     
     
         17 . A combined system therapy and imaging system comprising:
 a radiation therapy apparatus;   a magnetic resonance (MR) imaging apparatus;   a control computer configured to operate the combined system in order to acquire MR signals from a subject during irradiation of the subject with a radiation beam having a central beam;   said control computer being configured to operate said MR imaging apparatus to acquire a three-dimensional MR volume data set that contains a target volume for irradiation with said radiation beam;   said control computer being configured to continuously determine a location of the central beam relative to the subject;   said control computer being configured to determine a further MR image data set that is positioned substantially perpendicularly to central beam and, if the location of the central beam changes, to acquire a changed second MR data set that is substantially perpendicular to the central beam; and   said control computer being configured to emit a control signal, dependent on said changed further MR data set, to said radiation therapy apparatus that changes said radiation beam.   
     
     
         18 . A non-transitory, computer-readable data storage medium encoded with programming instructions, said storage medium being loaded into a computer system of a combined system comprising a radiation therapy apparatus and a magnetic resonance (MR) imaging apparatus, said programming instructions causing said computer system to:
 operate the combined system to acquire MR signals from a subject during irradiation of the subject with a radiation beam having a central beam;   operate said MR imaging apparatus to acquire a three-dimensional MR volume data set that contains a target volume for irradiation with said radiation beam;   continuously determine a location of the central beam relative to the subject;   determine a further MR image data set that is positioned substantially perpendicularly to central beam and, if the location of the central beam changes, acquire a changed second MR data set that is substantially perpendicular to the central beam; and   emit a control signal, dependent on said changed further MR data set, to said radiation therapy apparatus that changes said radiation beam.