Pet/mri device, pet device, and image reconstruction system

Abstract

A PET/MRI device includes an MRI device that has a measurement port, a PET detector that can be inserted into the measurement port, and a mechanism that can slide the PET detector into and out of the MRI measurement port. Thereby, the PET/MRI device allows MRI measurement during PET measurement.

1 . A PET/MRI device comprising:
 an MRI device that has a measurement port;   a PET detector that is insertable into the measurement port; and   a mechanism that is capable of sliding the PET detector into and out of the measurement port of the MRI device, MRI measurement being allowed during PET measurement.   
     
     
         2 . The PET/MRI device according to  claim 1 , wherein the PET detector has a measurement field of view having a width wider than that of the MRI device in a longitudinal direction of a measurement object. 
     
     
         3 . The PET/MRI device according to  claim 1 , wherein the PET detector is movable through the measurement port with the measurement object. 
     
     
         4 . The PET/MRI device according to  claim 1 , wherein the PET detector is attached to a bed of the measurement object for integral movement. 
     
     
         5 . The PET/MRI device according to  claim 4 , further comprising a mechanism that is capable of sliding the PET detector in a longitudinal direction of the bed on which the measurement object is put. 
     
     
         6 . The PET/MRI device according to  claim 1 , wherein an MRI RF coil is attached to inside the PET detector. 
     
     
         7 . The PET/MRI device according to  claim 6 , wherein the MRI RF coil attached to inside the PET detector is a transmitter coil, a receiver coil, a transmitter-receiver two-way coil, or a coil that includes both a transmitter coil and a receiver coil. 
     
     
         8 . The PET/MRI device according to  claim 2 , wherein the width of the measurement field of view of the PET detector is extended to cover the measurement object at least from a head to a trunk thereof. 
     
     
         9 . The PET/MRI device according to  claim 8 , wherein the PET detector is divided in the longitudinal direction of the measurement object. 
     
     
         10 . The PET/MRI device according to  claim 8 , wherein detector rings that constitute the PET detector, and/or detector units that constitute the detector rings, are arranged at nonuniform intervals. 
     
     
         11 . The PET/MRI device according to  claim 8 , wherein PET detectors having different resolutions and/or sensitivities are used for a head and a trunk, respectively. 
     
     
         12 . The PET/MRI device according to  claim 11 , wherein the PET detector for a head has a resolution higher than that of the PET detector for the trunk. 
     
     
         13 . The PET/MRI device according to  claim 8 , wherein the PET detector for a head includes a detector ring that has an inner diameter smaller than that of a detector ring that constitutes the PET detector for a trunk. 
     
     
         14 . The PET/MRI device according to  claim 1 , wherein the PET detector has an opening in at least an eye-covering area near a head of the measurement object. 
     
     
         15 . The PET/MRI device according to  claim 1 , wherein a detector ring that constitutes the PET detector near a trunk of the measurement object has a sectional shape such that a size thereof in a thickness direction of the measurement object is different from that in a width direction perpendicular to the thickness direction so that the detector approaches a surface of the trunk. 
     
     
         16 . The PET/MRI device according to  claim 15 , wherein the detector ring that constitutes the PET detector near the trunk of the measurement object includes an arched upper half portion and an arched lower half portion in the thickness direction of the measurement object, the arched upper half portion having a radius of curvature smaller than that of the arched lower half portion. 
     
     
         17 . The PET/MRI device according to  claim 1 , wherein the detector ring that constitutes the PET detector has an arched upper half portion in the thickness direction of the measurement object, the arched upper half portion being openable at least in part. 
     
     
         18 . The PET/MRI device according to  claim 17 , wherein the arched upper half portion is opened in a double-door configuration. 
     
     
         19 . The PET/MRI device according to  claim 17 , wherein the arched upper half portion is opened in a single-door configuration. 
     
     
         20 . The PET/MRI device according to  claim 17 , wherein the arched upper half portion and a remaining arched lower half portion are separable from each other. 
     
     
         21 . The PET/MRI device according to  claim 3 , wherein the detector ring that constitutes the PET detector has an arched upper half portion in the thickness direction of the measurement object, the arched upper half portion being variable in size and/or in shape according to the measurement object. 
     
     
         22 . The PET/MRI device according to  claim 9 , wherein the PET detector for a head is movable with respect to and/or detachable from the PET detector for a trunk. 
     
     
         23 . The PET/MRI device according to  claim 1 , wherein the PET measurement is started before the PET detector starts being slid into the measurement port of the MRI device, and ended after the PET detector ends being slid to a retracted position of the measurement object after end of the MRI measurement, whereby PET measurement time is maximized. 
     
     
         24 . The PET/MRI device according to  claim 1 , wherein the PET detector includes a mechanism for sliding inside the measurement port independent of a sliding movement of the measurement object, so that the PET detector slides at a moving speed lower than that at which the measurement object slides. 
     
     
         25 . The PET/MRI device according to  claim 24 , comprising a slide mechanism that is capable of retracting the PET detector into the measurement port of the MRI device so as to facilitate loading and unloading of the measurement object onto/from the bed and setup of the measurement object. 
     
     
         26 . The PET/MRI device according to  claim 1 , wherein the PET measurement is started immediately before start of the MRI measurement and ended immediately after end of the MRI measurement, or PET data that is collected from immediately before the start of the MRI measurement to immediately after the end of the MRI measurement is used for PET image reconstruction processing, so as to improve simultaneity between the PET measurement and the MRI measurement. 
     
     
         27 . A PET device comprising a PET detector attached to a bed of a measurement object. 
     
     
         28 . The PET device according to  claim 27 , comprising a mechanism that is capable of sliding the PET detector in a longitudinal direction of the bed on which the measurement object is put. 
     
     
         29 . The PET device according to  claim 27 , wherein a width of a measurement field of view of the PET detector is extended to cover the measurement object at least from a head to a trunk thereof. 
     
     
         30 . The PET device according to  claim 29 , wherein the PET detector is divided in the longitudinal direction of the measurement object. 
     
     
         31 . The PET device according to  claim 29 , wherein detector rings that constitute the PET detector, and/or detector units that constitute the detector rings, are arranged at nonuniform intervals. 
     
     
         32 . The PET device according to  claim 29 , wherein PET detectors having different resolutions and/or sensitivities are used for a head and a trunk, respectively. 
     
     
         33 . The PET device according to  claim 32 , wherein the PET detector for a head has a resolution higher than that of the PET detector for the trunk. 
     
     
         34 . The PET device according to  claim 29 , wherein the PET detector for a head includes a detector ring that has an inner diameter smaller than that of a detector ring that constitutes the PET detector for a trunk. 
     
     
         35 . The PET device according to  claim 29 , wherein the PET detector has an opening in at least an eye-covering area near a head of the measurement object. 
     
     
         36 . The PET device according to  claim 27 , wherein a detector ring that constitutes the PET detector near a trunk of the measurement object has a sectional shape such that a size thereof in a thickness direction of the measurement object is different from that in a width direction perpendicular to the thickness direction so that the detector approaches a surface of the trunk. 
     
     
         37 . The PET device according to  claim 36 , wherein the detector ring that constitutes the PET detector near the trunk of the measurement object includes an arched upper half portion and an arched lower half portion in the thickness direction of the measurement object, the arched upper half portion having a radius of curvature smaller than that of the arched lower half portion. 
     
     
         38 . The PET device according to  claim 27 , wherein the detector ring that constitutes the PET detector has an arched upper half portion in the thickness direction of the measurement object, the arched upper half portion being openable at least in part. 
     
     
         39 . The PET device according to  claim 38 , wherein the arched upper half portion is opened in a double-door configuration. 
     
     
         40 . The PET device according to  claim 38 , wherein the arched upper half portion is opened in a single-door configuration. 
     
     
         41 . The PET device according to  claim 38 , wherein the arched upper half portion and a remaining arched lower half portion are separable from each other. 
     
     
         42 . The PET device according to  claim 27 , wherein the PET detector includes a detector ring at least whose upper portion above a bed covering the measurement object is variable in size and/or in shape according to the measurement object. 
     
     
         43 . The PET device according to  claim 30 , wherein the PET detector for a head is movable with respect to and/or detachable from the PET detector for a trunk. 
     
     
         44 . A PET device comprising a belt-like PET detector that is composed of detector units connected by links, the detector units being freely changeable in layout according to a shape of a measurement object. 
     
     
         45 . The PET device according to  claim 44 , wherein the links has a function of allowing rotation and a change in distance between the detector units. 
     
     
         46 . The PET device according to  claim 44 , wherein the links includes an encoder so that a relationship in spatial position coordinates between adjoining detector units is obtainable. 
     
     
         47 . The PET device according to  claim 44 , comprising an inner frame so that the detector units constituting the belt-like PET detector are located in predetermined positions. 
     
     
         48 . The PET device according to  claim 47 , wherein a plurality of types of the inner frame are prepared in advance according to size and/or shape of the measurement object. 
     
     
         49 . An image reconstruction system for calculating a system matrix element for use in an image reconstruction operation by: referring to a relationship in spatial position coordinates between adjoining ones of detector units that are connected into a belt-like PET detector by links, the relationship being acquired from encoders attached to the links; referring to spatial position coordinates of the detector units constituting the belt-like PET detector, the coordinates being determined by an inner frame for locating the detector units in predetermined positions; or referring to spatial position coordinates of the detector units, determined by an arched upper half portion of the PET detector. 
     
     
         50 . The image reconstruction system according to  claim 49 , wherein system matrices corresponding to respective layout patterns of detector units are calculated in advance and stored in a storing device, the layout patterns being uniquely determined by types of an inner frame or an arched upper half portion of a PET detector.