Abstract:
An X-ray imaging system is disclosed which can effect positioning of an X-ray irradiator and an X-ray receiver in an adaptive manner. The X-ray imaging system uses an X-ray irradiator and an X-ray receiver opposed to each other through a space to radiograph a subject positioned between the two and comprises radiographing device having the X-ray irradiator and the X-ray receiver, optical radiographing device for picking up an optical image of the subject, specifying device for analyzing the optical image and specifying physical characteristics of the subject, and positioning device for positioning the X-ray irradiator and the X-ray receiver of the radiographing device on the basis of the specified physical characteristics and a portion to be radiographed of the subject.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Chinese Patent Application No. 200710102911.5 filed May 11, 2007, and incorporated herein in its entirety. 
     BACKGROUND OF THE INVENTION 
     The subject matter disclosed herein relates to an X-ray imaging system and more particularly to an X-ray imaging system using an X-ray irradiator and an X-ray receiver opposed to each other through a space to radiograph a subject positioned between the two. 
     In an X-ray imaging system there are used an X-ray irradiator and an X-ray receiver opposed to each other through a space to radiograph a subject positioned between them. Positioning of the X-ray irradiator and the X-ray receiver is performed in the X-ray imaging system. The positioning is effected by adjusting the position and attitude of each of the X-ray irradiator and the X-ray receiver to match the constitution of the subject and a portion to be radiographed of the subject (see, for example, Japanese Unexamined Patent Publication No. Hei 10 (1998)-057360). 
     Among X-ray imaging systems there is one wherein positioning of an X-ray irradiator and that of an X-ray receiver is performed automatically. However, since this positioning is an automatic positioning to a preset default state, it is impossible to cope with an individual difference between subjects. 
     Accordingly, it is an object of the present invention to provide an X-ray imaging system which carries out positioning of an X-ray irradiator and that of an X-ray receiver in an adaptive manner. 
     SUMMARY OF THE INVENTION 
     According to the present invention for solving the above-mentioned problem there is provided an X-ray imaging system using an X-ray irradiator and an X-ray receiver opposed to each other through a space to radiograph a subject positioned between the two, the X-ray imaging system comprising radiographing device having the X-ray irradiator and the X-ray receiver, optical radiographing device for picking up an optical image of the subject, specifying device for analyzing the optical image and specifying physical characteristics of the subject, and positioning device for positioning the X-ray irradiator and the X-ray receiver of the radiographing device on the basis of the specified physical characteristics and a portion to be radiographed of the subject. 
     It is preferable in point of effective positioning that the radiographing device comprise: first support device for supporting the X-ray irradiator movably in two horizontal directions orthogonal to each other and also in the vertical direction and rotatably about two axes orthogonal to each other; and second support device for supporting the X-ray receiver vertically movably and in such a manner as the direction of a light receiving surface being changeable. 
     It is preferable in point of effective positioning that the radiographing device comprise: first support device for supporting the X-ray irradiator movably in two horizontal directions orthogonal to each other and also in the vertical direction and rotatably about two axes orthogonal to each other; and a table for supporting a top board as a subject carrier vertically movably and supporting the X-ray receiver under the top board horizontally movably. 
     It is preferable in point of effective positioning that the radiographing device comprise first support device for supporting the X-ray irradiator movably in two horizontal directions orthogonal to each other and also in the vertical direction and rotatably about two axes orthogonal to each other, second support device for supporting the first X-ray receiver vertically movably and in such a manner as the direction of a light receiving surface being changeable, and a table for supporting a top board as a subject carrier vertically movably and supporting the second X-ray receiver under the top board horizontally movably. 
     It is preferable in point of effectively positioning the X-ray irradiator that the first support device be an overhead tube suspension. 
     it is preferable in point of effectively positioning the X-ray detector that the second support device be a wall stand. 
     The X-ray imaging system according to the present invention uses an X-ray irradiator and an X-ray receiver opposed to each other through a space to radiograph a subject positioned between the two and comprises radiographing device having the X-ray irradiator and the X-ray receiver, optical radiographing device for picking up an optical image of the subject, specifying device for analyzing the optical image and specifying physical characteristics of the subject, and positioning device for positioning the X-ray irradiator and the X-ray receiver of the radiographing device on the basis of the specified physical characteristics and a portion to be radiographed of the subject. Therefore, the X-ray imaging system can effect positioning of the X-ray irradiator and that of the X-ray receiver in an adaptive manner. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing the configuration of an X-ray imaging system according to an example of the best mode for carrying out the present invention. 
         FIG. 2  is a diagram showing an example of the appearance of an X-ray irradiating unit. 
         FIG. 3  is a diagram showing an example of the appearance of an X-ray receiving unit. 
         FIG. 4  is a diagram showing an example of the appearance of a radiographing table. 
         FIG. 5  is a diagram showing the plan of a radiographing chamber and a layout example of various components in the chamber. 
         FIG. 6  is a block diagram from the standpoint of auto-positioning of the X-ray imaging system as an example of the best mode for carrying out the present invention. 
         FIG. 7  is a flow chart showing operations of the X-ray imaging system as an example of the best mode for carrying out the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The best mode for carrying out the invention will be described in detail hereinunder with reference to the drawings. The present invention is not limited to the best mode for carrying out the invention.  FIG. 1  shows a schematic configuration of an X-ray imaging system. This system is an example of the best mode for carrying out the invention. With the configuration of this system there is shown an example of the best mode for carrying out the invention in connection with the X-ray imaging system. 
     As shown in  FIG. 1 , this system has an X-ray irradiating unit  100 , an X-ray receiving unit  200 , a radiographing table  300 , a camera  400  and an operator console  500 . The section comprising the X-ray irradiating unit  100 , X-ray receiving unit  200  and radiographing table  300  is an example of the radiographing device in the present invention. The camera  400  is an example of the optical photographing device in the present invention. 
     The X-ray irradiating unit  100  is configured to support an X-ray irradiator  120  at a lower end of a column  110  hanging from a ceiling. Such a support mechanism is also called an overhead tube suspension. The overhead tube suspension is an example of the first support device in the present invention. The X-ray irradiator  120  is an example of the X-ray irradiator in the present invention. 
     The column  110  can extend and contract in the vertical direction and is movable horizontally along the ceiling. The direction of horizontal moving is two directions orthogonal to each other. At the lower end of the column  110  the X-ray irradiator  120  is rotatable about two axes orthogonal to each other. The extension and contraction, as well as the horizontal movement in two directions, of the column  110  and the biaxial rotation of the X-ray irradiator  120  are each performed by utilizing power of a motor for example.  FIG. 2  shows the appearance of an example of the X-ray irradiating unit  100 . 
     The X-ray receiving unit  200  is configured in such a manner that a carriage  220  is supported vertically movably by a column  210  perpendicular to a floor, an arm  230  is supported horizontally by the carriage  220 , and a first X-ray receiver  240  is supported by a front end of the arm  230 . Such a support mechanism is also called a wall stand. The wall stand is an example of the second support device in the present invention. The X-ray receiver  240  is an example of the X-ray receiver in the present invention. 
     The X-ray receiver  240  is a flat plate-like structure and the direction of a light receiving surface thereof can be changed to match an incidence direction of X-ray. The direction of the light receiving surface is typically horizontal or vertical, but this constitutes no limitation and there may be adopted any other direction. The vertical movement of the carriage  220  and changing the direction of the light receiving surface of the first X-ray receiver  240  are each performed by utilizing power of a motor for example.  FIG. 3  shows the appearance of an example of the X-ray receiving unit  200 . 
     The radiographing table  300  has a top board  310 . The radiographing table  300  is an example of the table in the present invention. The top board  310  of the radiographing table  300  is a horizontal board and is movable vertically with respect to the floor. A subject is rested on the top board  310 . An X-ray receiver  340  is disposed under the top board  310 . The X-ray receiver  340  is an example of the X-ray receiver in the present invention.  FIG. 4  shows the appearance of an example of the radiographing table  300 . 
     The X-ray receiver is movable horizontally. The vertical movement of the top board  310  and the horizontal movement of the second X-ray receiver  340  are each performed by utilizing power of a motor for example. 
     The camera  400  functions to pick up an optical image. For example, there is used a digital camera. The camera  400  is used to pick up an optical image of the subject before the radiographing. 
     The operator console  500  controls the X-ray irradiating unit  100 , X-ray receiving unit  200  and radiographing table  300 . As to the X-ray irradiating unit  100 , the operator console  500  performs auto-positioning of the X-ray irradiator  120  and controls the intensity of X-ray, as well as irradiation time and irradiation timing. As to auto-positioning of the X-ray irradiator  120 , a description will be given again later. 
     As to the X-ray receiving unit  200 , the operator console  500  performs auto-positioning of the first X-ray receiver  240 . As to the radiographing table  300 , the operator console  500  not only controls raising and lowering of the top board  310  but also performs auto-positioning of the second X-ray receiver  340 . Auto-positioning of the first X-ray receiver  240  is performed when radiographing the subject with use of the first X-ray receiver  240 , while auto-positioning of the second X-ray receiver  340  is performed when radiographing the subject with use of the second X-ray receiver  340 . As to auto-positioning of the first X-ray receiver  240  and that of the second X-ray receiver  340 , a description will be given again later. 
     A signal detected by the first X-ray receiver  240  is inputted to the operator console  500 . In accordance with the input signal from the first X-ray receiver  240  the operator console  500  re-construct a radioscopic image of the subject and displays it on a display  510 . The X-ray receivers  240  and  340  may be formed of a photosensitive material sensitive to X-ray. In this case, the radioscopic image rendered visible by a developing process. 
     An optical image picked up by the camera  400  is inputted to the operator console  500 . The operator console  500  analyses the optical image and specifies physical characteristics of the subject. The specified physical characteristics are, for example, stature, body thickness, style and skin condition. The operator console  500  utilizes there physical characteristics in the auto-positioning of the X-ray irradiator  120  and X-ray receivers  240  and  340 . 
       FIG. 5  shows the plan of a radiographing chamber and a layout example of various components. As shown in  FIG. 5 , the radiographing chamber has a preparation compartment  2 , a shielded compartment  4  and an operation compartment  6 . These compartments have respective doors for entrance and exit among them. The shielded compartment  4  is shielded with lead plates or the like to prevent leakage of X-ray to the exterior. The shielded compartment  4  is provided with a window so that the interior thereof can be observed from the operation compartment  6  side. This window also possesses X-ray shieldability. 
     The camera  400  is installed in the preparation compartment  2 . The X-ray irradiating unit  100 , X-ray receiving unit  200  and radiographing table  300  are installed in the shielded compartment  4 . In the operation compartment  6 , the operator console  500  is installed by the window of the shielded compartment  4 . 
     A subject  10  first enters the preparation compartment  2 , in which an optical image thereof is picked up. Thereafter, the subject enters the shielded compartment  6 . In the shielded compartment  6 , the subject either stands up before the X-ray receiving unit  200  or lies down on the radiographing table  300 . 
       FIG. 6  is a block diagram of this system as seen from the standpoint of auto positioning. The operator console  500  has an image analyzer  502 , a protocol selector  504  and an auto-positioner  506 . 
     An optical image picked up by the camera is inputted to the image analyzer  502 . The image analyzer  502  analyzes the optical image and specifies physical characteristics of the subject. The specifying of physical characteristics is performed using, for example, an expert system. The specified physical characteristics are inputted to the auto-positioner  506 . The image analyzer  502  is an example of the specifying device in the present invention. 
     In accordance with operation performed by an operator the protocol selector  504  selects, for example, head, breast, abdomen, or extremities. Information indicative of the selected portion to be radiographed is inputted to the auto-positioner  506 . 
     The auto-positioner  506  outputs a signal based on the physical characteristics of the subject and the information on the portion to be radiographed to effect auto-positioning of a radiographing section  600 . The auto-positioner  506  is an example of the positioning device in the present invention. The radiographing section  600  is made up of the X-ray irradiating unit  100 , X-ray receiving unit  200  and radiographing table  300 . 
       FIG. 7  is a flow chart showing operations of this system. As shown in  FIG. 7 , an optical image pick-up operation is performed in step  71 . This is done using the camera  400 . In this way there is obtained an optical image of the subject  10 . 
     In step  72  there is performed specifying of physical properties. This is done by analyzing the optical image of the subject  10  in the image analyzer  502 . In this way there are specified, for example, stature, body thickness, style and skin condition. 
     In step  73  there is performed protocol selection. This is done by the protocol selector  504  on the basis of operation performed by the operator. In this way there is selected, for example, head, breast, abdomen, or extremities, as the portion to be radiographed. 
     In step  74  there is performed auto-positioning. This is done by the auto-positioner  506 . In order that the to-be-radiographed portion designated by the protocol selection can be radiographed, the auto-positioner  506  not only adjusts the position and angle of the X-ray irradiator  120  in conformity with the stature, body thickness, style, etc. of the subject  10  but also adjusts the position of the first X-ray receiver  240  or  340  in conformity with the position and angle of the X-ray irradiator  120 . As to the first X-ray receiver  240 , the direction of its light receiving surface is also adjusted. 
     Thus, positioning of the X-ray irradiator  120 , X-ray receiver  240  and X-ray receiver  340  is performed automatically in accordance with physical characteristics of the subject  10  and the portion to be radiographed of the subject. Therefore, the system can thoroughly cope with various subjects different in stature, body thickness, style, etc. 
     In step  75  there is performed radiographing. The radiographing is performed under control by the operator console  500 . The operator console  500  performs radiographing while matching radiographing conditions such as tube voltage, tube current, irradiation time and irradiation timing to the purpose of radiographing. The physical characteristics specified in step  72 , e.g., body thickness, can be utilized for setting the radiographing conditions. 
     The age inputted at the time of patient registration may be utilized for setting the radiographing conditions. The age can also be utilized for determining a bone density from X-ray transmittance. There may be adopted a method wherein the state of respiration is monitored using a sensor attached to a patient and X-ray is radiated in conformity with a gentle respiration period. Further, the state of skin obtained by image analysis may be utilized in for example estimating the condition of a disease.