Abstract:
A multimodality imaging system, comprising: a first imaging system for forming a first image; a second imaging system for forming a second image; and a rotating device on which the first imaging system and the second imaging system are fixed so that the first imaging system and the second imaging system are selectively rotated to a scanning position.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a medical apparatus, and particularly to a multimodality imaging system. 
         [0003]    2. Description of the Related Art 
         [0004]    When using a multimodality imaging system including medical apparatuses such as a CT (Computerized Tomography) apparatus, a MRI (Magnetic Resonance Imaging) apparatus, a PET (Positron Emission Tomography) apparatus, a SPECT (Single Photon Emission Computed Tomography) apparatus, in order to assure the effectiveness of synthesis of images formed by different apparatuses, it must be assured that an extent of deformation of a bed pallet is uniform at different detector positions when a patient on the bed pallet is scanned in the multimodality imaging system. Only when the extent of deformation is uniform, could it be assured that the image fusion is correct and positive to the effect of the diagnoses. When a patient is scanned with a PET apparatus  11  and a CT apparatus  12 , an extent of deformation of a bed pallet is not uniform due to different lengths that the bed pallet extends at a PET scanning plane  13  and a CT scanning plane  14 , that is, Y 1  is not equal to Y 2 , as shown in  FIG. 1 . As a result, it cannot be assured that the image fusion is correct, thus degrading the effect of the diagnoses on the patient. 
       SUMMARY 
       [0005]    It is an object of the present invention to provide a multimodality imaging system capable of assuring that a moving trajectory of a patient is uniform when the patient is scanned at different subsystems and that positions of the subsystems remain constant before and after maintenance of apparatuses of the system. 
         [0006]    In accordance with one aspect of the present invention, there is provided a multimodality imaging system comprising a first imaging system for forming a first image; a second imaging system for forming a second image; and a rotating device on which the first imaging system and the second imaging system are fixed so that the first imaging system and the second imaging system are selectively rotated to a scanning position. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
           [0008]      FIG. 1  is a schematic view showing difference of deformation extent of a bed pallet due to difference of lengths that the bed pallet extends. 
           [0009]      FIG. 2   a  is a schematic view showing operating principle of PET/CT equipment with a rotating base in a state that a bed frame is stationarily fixed on a floor surface while the PET/CT equipment is mounted on the rotating base. 
           [0010]      FIG. 2   b  is a schematic view showing operating principle of PET/CT equipment with a rotating base in a state that the PET/CT equipment is stationarily fixed on a floor surface while a bed frame is mounted on the rotating base. 
           [0011]      FIG. 3   a  is a schematic view showing components of a multimodality imaging system in which a bed frame is stationarily fixed on a floor surface while PET/CT equipment is mounted on a rotating base. 
           [0012]      FIG. 3   b  is a schematic view showing components of a multimodality imaging system in which PET/CT equipment is stationarily fixed on a floor surface while a bed frame is mounted on a rotating base. 
           [0013]      FIG. 4  is a schematic view showing a rotation mechanism of a base. 
           [0014]      FIG. 5  is a schematic view showing positions at which two mechanical positioning sleeve parts are assembled. 
           [0015]      FIG. 6  is a schematic view showing the mechanical positioning sleeve parts of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    A multimodality imaging system according to an embodiment of the present invention comprises a first imaging system CT  22 ′ (having a scanning plane  22 ) and a second imaging system PET  23 ′ (having a scanning plane  23 ) mounted on a rotating base  24  according to the present invention, and a bed with a bed body mounted on a floor surface as shown in  FIG. 2   a . The first imaging system CT  22 ′ (having the scanning plane  22 ) is positioned adjacent to a patient, and the second imaging system PET  23 ′ (having the scanning plane  23 ) is positioned away from the patient. When the first imaging system CT  22 ′ (having the scanning plane  22 ) begins to scan the patient, a bed pallet  21  extends a length of A. After the first imaging system CT  22 ′ (having the scanning plane  22 ) has scanned the patient, the rotating base  24  is rotated by or through 180° in a certain direction, so that the second imaging system PET  23 ′ (having the scanning plane  23 ) is positioned adjacent to the patient. The first imaging system CT  22 ′ (having the scanning plane  22 ) and the second imaging system PET  23 ′ (having the scanning plane  23 ) are mounted at an appropriate position on the rotating base  24  by accurately calculating positional relationship between the first imaging system CT  22 ′ (having the scanning plane  22 ) and the second imaging system PET  23 ′ (having the scanning plane  23 ). As a result, it can be, assured that the bed pallet  21  still extends the length of A when the second imaging system PET  23 ′ (having the scanning plane  23 ) begins to scan the patient. Therefore, it can be assured that deformation of the bed pallet  21  is uniform in both the first imaging system CT  22 ′ (having the scanning plane  22 ) and the second imaging system PET  23 ′ (having the scanning plane  23 ). 
         [0017]    A multimodality imaging system according to another embodiment of the present invention comprises a first imaging system CT  22 ′ (having a scanning plane  22 ) and a second imaging system PET  23 ′ (having a scanning plane  23 ) mounted on a floor surface on both sides of a rotating base  24  according to the present invention, as shown in  FIG. 2   b . The scanning planes  22 ,  23  of the first imaging system CT  22 ′ and the second imaging system PET  23 ′ are parallel to each other and symmetrical with respect to an axis of the rotating base. In addition, the multimodality imaging system further comprises a bed with a bed body. The bed body is mounted on the rotating base  24 . The first imaging system CT  22 ′ (having the scanning plane  22 ) is positioned adjacent to a patient, and the second imaging system PET  23 ′ (having the scanning plane  23 ) is positioned away from the patient. When the first imaging system CT  22 ′ (having the scanning plane  22 ) begins to scan the patient, the bed pallet  21  extends a length of A. After the first imaging system CT  22 ′ (having the scanning plane  22 ) has scanned the patient, the rotating base  24  is rotated by 180° in a certain direction, so that the second imaging system PET  23 ′ (having the scanning plane  23 ) is positioned adjacent to the patient. The first imaging system CT  22 ′ (having the scanning plane  22 ) and the second imaging system PET  23 ′ (having the scanning plane  23 ) are mounted at an appropriate position on the floor surface on both sides of the rotating base  24  by calculating positional relationship between the first imaging system CT  22 ′ (having the scanning plane  22 ) and the second imaging system PET  23 ′ (having the scanning plane  23 ) with accuracy. As a result, it can be assured that the bed pallet  21  still extends the length of A when the second imaging system PET  23 ′ (having the scanning plane  23 ) begins to scan the patient. Therefore, it can be assured that deformation of the bed pallet  21  is uniform in both the first imaging system CT  22 ′ (having the scanning plane  22 ) and the second imaging system PET  23 ′ (having the scanning plane  23 ). 
         [0018]    In some alternative embodiments, a movable patient table, a movable holder, or a movable patient supporting device is used instead of the bed. 
         [0019]    The rotatable base may be adjustable and comprises: a base disk  53  as shown in  FIG. 5 , an external gear type rotary bearing (including a rotary bearing inner ring  414  and an outer ring  412 ), a pinion  402 , a shaft  403 , a coupling  405 , a worm-gear speed reducer  406  (or a bevel-gear speed reducer or other reducer), a motor  408  with a brake, a support  407 , and a base disk stand  409 . The base disk  53  shown in  FIG. 5  is coupled with the outer ring  412  of the external gear type rotary bearing by bolts  411  and positioning pins  413  shown in  FIG. 4 . The inner ring  414  of the external gear type rotary bearing is coupled with the base disk stand  409  by bolts  411  and positioning pins  413  shown in  FIG. 4 . The support  407  is used to hold the worm-gear speed reducer  406 , the pinion  402 , the shaft  403 , and the coupling  405 . The motor  408  with the brake is coupled with a flange of a housing of the worm-gear speed reducer  406  by bolts, and the support  407  is connected to the base disk stand  409  by welding or bolts. The pinion  402  meshes with an external gear on the outer ring  412  of the external gear type rotary bearing as shown in  FIG. 4 , so that the motor with the brake rotates the base disk  53  by the worm-gear speed reducer  406 , the pinion  402  and the external gear on the outer ring  412  of the external gear type rotary bearing (including a rotary bearing inner ring  414  and a outer ring  412 ). A capacitive proximity switch support  401  is fixed at an appropriate position on an upper surface of the outer ring  412  of the external gear type rotary bearing, and a capacitive proximity switch  415  is fixed at an appropriate position on the capacitive proximity switch support  401 . An inclined metal block  410  is fixed at an appropriate position on the inner ring  412 . The capacitive proximity switch  415  is a position sensor capable of outputting a value indicative of the opening/closing degree or extent thereof. A measuring probe of the capacitive proximity switch  415  usually is a plate of a capacitor, while the other plate of the capacitor is an object itself. When the object is approaching the proximity switch, a dielectric constant between the object and the proximity switch is changed, so that a state of an electric circuit connected with the measuring probe is accordingly changed. As a result, the proximity switch is controlled to be turned on and off. An encoder  404  shown in  FIG. 4  is connected to an end of a worm of the worm-gear speed reducer  406 . When the base disk  53  rotates by or through about 160°, the capacitive proximity switch  415  approaches the inclined metal block  410  shown in  FIG. 4 . The dielectric constant of the capacitive proximity switch  415  is changed, so that the state of the electric circuit connected with the measuring probe is accordingly changed. The capacitive proximity switch  415  sends a control signal to control the motor  408  to be decelerated together with the encoder  404 . When the base disk is rotated by or through 180°, the capacitive proximity switch  415  sends control signal to control the motor  408  to be braked and stopped. Since the two-stage speed reducing system having the worm-gear speed reducer  406  with a speed reducing ratio of about 40 and the pinion-outer gear reducer with a speed reducing ratio of about 6 is selected, the base disk  53  shown in  FIG. 5  rotates at a speed of about 6 rpm before the capacitive proximity switch sends the control signal to instruct the motor with the brake to be decelerated. In the operating condition that the rotating speed of the base disk is not high, as shown in  FIG. 5 , two ball head plunger type positioning post sleeve parts  51  and  52 , positions of which can be adjusted with accuracy, are mounted at appropriate positions on a floor surface perpendicular to an edge of the base disk  53 , respectively, and are positioned at 180° with respect to each other. Each of the positioning post sleeve parts  51  and  52  comprises an anchor plate  61  shown in  FIG. 6 . When the system is mounted, the anchor plate  61  is firmly connected to the floor surface by anchor bolts or expansion bolts, and is fixed with the floor surface by pouring concrete around the anchor plate  61 , so that it is assured that the anchor plates  61  of the positioning post sleeve parts  51  and  52  are firmly connected with the floor surface. When the positioning post sleeve parts  51  and  52  are mounted and adjusted, four finely adjusting bolts  62  on each of the anchor plates  61  of the positioning post sleeve parts  51  and  52 , and a finely adjusting nut  66  on a top of each of the positioning post sleeve parts  51  and  52  are finely adjusted, so that a ball  67  of a ball head plunger type positioning post  64  of each of the ball head plunger type positioning post sleeve parts  51  and  52  is just fitted in a stopping point recess  68  formed in the edge of the base disk  53 . Then, nuts  63  and bolts  65  of each of the ball head plunger type positioning post sleeve parts  51  and  52  are screwed down (see  FIG. 6 ). As a result, when the motor  408  with the brake (shown in  FIG. 4 ) is stopped, the base disk  53  can be positioned with accuracy. The base disk  53  is adapted to fix a plurality of imaging apparatuses. The base disk stand is adapted to bear the load of the plurality of imaging apparatuses so that the overall load of the plurality of imaging apparatuses is distributed uniformly. The adjustable rotating base can provide the plurality of imaging apparatuses with the different rotating angles. 
         [0020]    The present invention effectively solves the inconsistence of deformation of the bed pallet in at least two imaging systems during scanning a patient by the rotating base and at the same time brings about a prominent advantage that there is no requirement for addition of length of the bed pallet during scanning a patient since the multimodality imaging system adopts the rotating base. As a result, the bed pallet can fulfill a requirement of the multimodality imaging system no matter which one of a first imaging system and a second system is used. It is thus possible for a medical establishment that has a first imaging system to constitute a multimodality imaging system by buying a second imaging system required, so that the medical establishment can greatly save cost for buying equipment. On the other hand, positions of the two imaging systems are fixed independently of each other by separately assembling the first imaging system and second imaging system on the rotating base with a distance therebetween which is enough for maintenance. No imaging system is required to be moved in maintenance, so that there is no need of realignment before and after the maintenance. Therefore, the present invention effectively solves a problem of maintenance of the multimodality imaging system. 
         [0021]    Operating processes of the multimodality imaging system according to the present invention are described as follows. 
       EXAMPLE 1 
       [0022]    When a patient is to be scanned by the first imaging system CT  22 ′ as shown in  FIG. 2   a , the bed pallet  21  is located at an original position, the first imaging system CT  22 ′ is positioned adjacent to the bed pallet  21 , and the second imaging system PET  23 ′ is positioned away from the bed pallet  21 . The bed pallet  21  is moved forward so that the patient is sent to the scanning plane  22  of the first imaging system CT  22 ′. Firstly, the patient is scanned by the first imaging system CT  22 ′. After the patient has been scanned by the first imaging system CT  22 ′, the bed pallet  21  is moved back to the original position from a scanning position. Then, the first imaging system CT  22 ′ and the second imaging system PET  23 ′ rotate by or through 180° by an automatic control device, so that the second imaging system PET  23 ′ is positioned adjacent to the bed pallet  21  and the first imaging system CT  22 ′ is positioned away from the bed pallet  21 . The bed pallet  21  is moved forward so that the patient is sent to the scanning plane  23  of the second imaging system PET  23 ′. Then, the patient is scanned by the second imaging system PET  23 ′. After the patient has been scanned by the second imaging system PET  23 ′, the bed pallet  21  is moved back to the original position. The scanning process is completed. Finally, the first imaging system CT  22 ′ and the second imaging system PET  23 ′ reversely rotate by or through 180° by the automatic control device, so that the first imaging system CT  22 ′ and the second imaging system PET  23 ′ are resumed to original positions thereof. In addition, the first imaging system CT  22 ′ and the second imaging system PET  23 ′ can maintain their respective full function abilities of clinic applications independently. 
       EXAMPLE 2 
       [0023]    When a patient is to be scanned by the first imaging system CT  22 ′ as shown in  FIG. 2   b , the bed pallet  21  is located at an original position, the first imaging system CT  22 ′ is positioned adjacent to the bed pallet  21 , and the second imaging system PET  23 ′ is positioned away from the bed pallet  21 . The bed pallet  21  is moved forward so that the patient is sent to the scanning plane  22  of the first imaging system CT  22 ′. Firstly, the patient is scanned by the first imaging system CT  22 ′. After the patient has been scanned by the first imaging system CT  22 ′, the bed pallet  21  is moved back to the original position from a scanning position. Then, the bed body rotates by or through 180° by an automatic control device, so that the second imaging system PET  23 ′ is positioned adjacent to the bed pallet  21  and the first imaging system CT  22 ′ is positioned away from the bed pallet  21 . The bed pallet  21  is moved forward so that the patient is sent to the scanning plane  23  of the second imaging system PET  23 ′. Then, the patient is scanned by the second imaging system PET  23 ′. After the patient has been scanned by the second imaging system PET  23 ′, the bed pallet  21  is moved back to the original position. The scanning process is completed. Finally, the bed body reversely rotates by or through 180° by the automatic control device, so that the bed body is resumed to an original position thereof. In addition, the first imaging system CT  22 ′ and the second imaging system PET  23 ′ can maintain their respective full function abilities of clinic applications independently. 
         [0024]    Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that modifications changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents. 
         [0025]    For example, in the above embodiments, a rotating device (the rotating base) is used so that the first imaging system and the second imaging system or the bed can be rotated, in order to assure that trajectories in which a patient is moved in different systems during scanning are consistent. However, the present application may use a moving manner, that is, a moving device movable on a guide, in stead of the rotating device. For example, the first imaging system and the second imaging system or the bed can be moved by a guide such as a rail and a moving device movable along the guide such as the rail, so as to assure that trajectories in which a patient, is moved in different systems during scanning are consistent. The moving manners include a translation manner and a composite motion manner. Therefore, the present invention can be achieved in a translation manner, a rotation manner, and a composite motion manner. 
         [0026]    For example, in an embodiment, a moving device according to the present application can achieve a translation, a rotation, and a composition motion. For example, a rotating device is disposed on an apparatus that can perform a translation and a composition motion, so that a moving device is formed. When the first imaging system and the second imaging system or a bed (or a patient supporting device) are mounted on the moving device, the first imaging system and the second imaging system or the bed (or the patient supporting device) can perform a translation, a rotation, and a composite motion so as to assure that trajectories in which a patient is moved in different systems during scanning are uniform. For example, a device for a translation and a composition motion may be a table movable on a guide such as a rail, a carriage movable along a guide such as a runner or a rail, and the like. 
         [0027]    For example, although the multimodality imaging system comprises only the first imaging system and the second imaging system in the above embodiments, it apparently may comprise a plurality of imaging systems such as 3, 4, 5, 6 or more imaging systems. 
         [0028]    In addition, although the first imaging system and the second imaging system are disposed at an angle of 180° with respect to each other in the above embodiments, they may be disposed at any appropriate angle with respect to each other. For example, the first imaging system and the second imaging system may be disposed at an angle within a range of 70-180° with respect to each other. 
         [0029]    Furthermore, although the first imaging system and the second imaging system and the bed body rotate by or through an angle of 180° so that the first imaging system and the second imaging system are respectively positioned at a position to start to scan a patient in the above embodiments, the rotation angle is apparently not limited to the angle of 70-180°. The first imaging system and the second imaging system and the bed body may rotate by or through any appropriate angle according to an angle at which the first imaging system and the second imaging system are disposed with respect to each other, so that the first imaging system and the second imaging system rotate in sequence to the position to start to scan a patient.