Abstract:
A medical image processing apparatus processes a medical image resulting from a medical image equipment. The apparatus comprises an interface, a processor, and a calculator. The interface is configured to obtain the medical image. The processor is configured to determine a smooth line along an embowed part of a specimen in the medical image obtained by the interface. The calculator is configured to calculate a bow scale of the embowed part based on the smooth line determined by the processor.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. P2002-100758, filed on Apr. 3, 2002, the entire contents of which are incorporated herein by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to a medical image processing apparatus which is operative to measure a predetermined part on a medical image obtained through a medical image equipment, such as, for example, an X-ray diagnosis apparatus. The present invention further relates to a method of measuring the predetermined part on the medical image obtained through the medical image equipment.  
         BACKGROUND OF THE INVENTION  
         [0003]    Medical image diagnoses have been rapidly progressing as computers have been improved since 1970&#39;s. The medical image diagnoses are accomplished by, for example, an X-ray diagnosis apparatus, an magnetic resonance imaging (MRI) apparatus, an X-ray computed tomography (CT) apparatus, or the like. Nowadays such diagnoses play a very important role for the medical practice. Medical images obtained by medical image equipments, such as those mentioned above, are usually observed and interpreted by a doctor or the like in his or her medical image diagnosis. In addition, the medical images may also be used, as a part of the diagnosis, for measuring a predetermined part of a patient&#39;s body, such as a organ and a bone. In a diagnosis of scoliosis as an example of bones diagnoses, a bow scale of the spine is calculated based on transmission images obtained in an X-ray diagnosis apparatus. It is said that scoliosis may occur when a spinal cord grows faster than its peripheral organs. Scoliosis tends to appear particularly in adolescent children who, therefore, are required a once-a-month follow-up.  
           [0004]    [0004]FIG. 1 is an illustration showing examples of measuring techniques of a bow scale in a diagnosis of scoliosis according to a prior art of the present invention. FIG. 1 (A) shows a measurement of the Cobb angles on a radiograph (image) of a patient or an examination object (hereinafter referred to as a specimen) for calculating bow angles. FIG. 1 (B) shows a measurement of the ‘Vertical-alignment’ distances on a radiograph (image) of the specimen for calculating deviations from a representative straight line along a spine, which is one as a hypothetically ideal healthy straight spine along a body axis of the specimen (hereinafter referred to as a median line). The median line may therefore be determined to indicate a center of a body axis of the specimen. The bow scale such as, for example, the Cobb angle and the ‘Vertical-alignment’ distance shows how much the spine is bent or curved. Basics of the Cobb angle and the ‘Vertical-alignment’ distance have been established and methods of such measurements are standards known in the art.  
           [0005]    In the Cobb angle calculation, as shown in FIG. 1 (A), an operator, such as a doctor or a radiological technologist, observes an X-ray transmission image (hereinafter referred to as an image) displayed in a display. The operator then determines by the eye (or determines with his or her sense) one or more points, such as points  1  to  3 , which are least bent points of a spine  4  (as long as the operator believes). Each adjacent two least bent points have a most bent point of the spine  4  between the each adjacent two points, based on the displayed image. At the determined points  1  to  3 , the operator manually draws perpendicular lines  5  to  7  perpendicular to tangent lines  8  to  10 , respectively, using, for example, a mouse. In detail, the operator determines the point  1 , and draws the tangent line  8  at the point  1 . Further, the operator draws the perpendicular line  5  perpendicular to the tangent line  8 . Similarly, the operator draws the perpendicular line  6  perpendicular to the tangent line  9  drawn at the determined point  2 . Still further, the operator draws the perpendicular line  7  perpendicular to the tangent line  10  drawn at the determined point  3 . A medical image processing apparatus connected to the display calculates angles α and β created by the perpendicular lines  5  to  7 . Namely, the perpendicular lines  5  and  6  cross with the angle α and similarly the perpendicular lines  6  and  7  cross with the angle β. The calculated angles α and β are displayed in the display.  
           [0006]    In the distance calculation of ‘Vertical-alignment’, as shown in FIG. 1 (B), the operator observes an image displayed in the display and draws a median line  11  along the spine  4 . The median line  11  is guessed and determined by the eye of the operator, based on the displayed image. The median line  11  intersects with the spine  4  at intersection points  12  to  14 . Then, the operator determines by the eye points  15  and  16  of the spine  4 , each of which is the furthest (as long as the operator believes) from the median line  11  between each two adjacent intersection points of the intersection points  12  to  14  when perpendicular lines are dropped to the median line  11  from the points  15  and  16 . In more detail, the operator determines the point  15  which is between the intersection points  12  and  13 . Further, the operator determines the point  16  which is between the intersection points  13  and  14 . The medical image processing apparatus calculates a distance  17  between the point  15  and the median line  11  when the perpendicular line is dropped to the median line  11  from the point  15 . Similarly, the medical image processing apparatus calculates a distance  18  between the point  16  and the median line  11  when the perpendicular line is dropped to the median line  11  from the point  16 . The calculated distances  17  and  18  are displayed in the display.  
           [0007]    In the prior art, scoliosis has been diagnosed using the calculated angles and/or distances as an index of the bow scale. The Cobb angle and the ‘Vertical-alignment’ distance have been conventionally obtained for the diagnosis of scoliosis based on the points and lines, which were selected and drawn in accordance with the determination by the operator&#39;s sense.  
           [0008]    Concretely, in the Cobb angle calculation, the points  1  to  3  of the spine  4  in the image displayed in the display were selected based on the operator&#39;s sense by observing the image with his or her eyes. Further, the tangent lines  8  to  10  and the perpendicular lines  5  to  7  were drawn based on the operator&#39;s sense by observing the image with his or her eyes. Similarly, in the ‘Vertical alignment’ distance calculation, the median line  11  was drawn based on the operator&#39;s sense by observing the image with his or her eyes. Further, the points  15  and  16  were selected based on the operator&#39;s sense by observing the image with his or her eyes.  
           [0009]    Therefore, the selected points and/or the drawn lines are quite subjective and accordingly the calculated result may be likely to be different among operators. Further, even when it is done by the same operator, the same result may not be reproduced if the operator does not have a clear standard for his or her determination of the selection and/or the drawing. Particularly, as mentioned above, the case of scoliosis may require the once-a-month follow-up of the bow scale of the spine. Therefore, the reproducibility should be kept and is a very important factor for the diagnosis of the scoliosis.  
           [0010]    One of factors contributing to the difficulty of the reproducibility (or the deterioration of the calculation accuracy) through the human being system may be as follows. The calculation is made for a very limited tiny region compared to the whole image displayed in the display. In addition, the state of bow of the spine is usually subtle and may be sometimes beyond the discrimination of the human beings. Therefore, the accuracy of the measurement result may not be assured in some cases.  
         BRIEF SUMMARY OF THE INVENTION  
         [0011]    According to a first aspect of the present invention, there is provided a medical image processing apparatus which processes a medical image resulting from a medical image equipment. The apparatus comprises an interface configured to obtain the medical image, a processor configured to determine a smooth line along an embowed part of a specimen in the medical image obtained by the interface, and a calculator configured to calculate a bow scale of the embowed part based on the smooth line determined by the processor.  
           [0012]    According to a second aspect of the present invention, there is provided a method of measuring a predetermined part in a medical image resulting from a medical image equipment. The method comprises steps of determining a smooth line along a embowed part of a specimen in the medical image, and automatically calculating a bow scale of the embowed part based on the smooth line.  
           [0013]    According to a third aspect of the present invention, there is provided a computer program product on which is stored a computer program for measuring a predetermined part in a medical image resulting from a medical image equipment. The computer program has instructions, which when executed, perform steps comprising determining a smooth line along a embowed part of a specimen in the medical image, and automatically calculating a bow scale of the embowed part based on the smooth line.  
           [0014]    According to a fourth aspect of the present invention, there is provided a medical image processing apparatus which processes a medical image resulting from a medical image equipment. The apparatus comprises an interface configured to obtain the medical image, a first processor configured to extract a profile of each vertebra of a spine in the medical image by a pattern recognition processing and obtain a gradient, against a horizontal line, of each of the vertebrae of the spine based on the extracted profile of each of the vertebrae, and a second processor configured to calculate a greatest angle, as a bow scale, between a first of the vertebrae of the spine with a positive gradient sign and a second of the vertebrae of the spine with a negative gradient sign based on the gradient of each of the vertebrae obtained by the first processor.  
           [0015]    According to a fifth aspect of the present invention, there is provided a method of measuring a predetermined part in a medical image resulting from a medical image equipment. The method comprises steps of extracting a profile of each vertebra of a spine in the medical image by a pattern recognition processing, obtaining a gradient, against a horizontal line, of each of the vertebrae of the spine based on the extracted profile of each of the vertebrae, and calculating a greatest angle, as a bow scale, between a first of the vertebrae of the spine with a positive gradient sign and a second of the vertebrae of the spine with a negative gradient sign based on the gradient of each of the vertebrae obtained by the first processor.  
           [0016]    According to a sixth aspect of the present invention, there is provided an X-ray diagnosis apparatus which comprises a generator, a detector, a mechanism, a synthesizer, a processor, and a calculator. The generator is configured to generate an X-ray. The detector is configured to detect a transmission X-ray transmitted from a specimen resulting from exposure of the X-ray to the specimen. The mechanism is configured to move the generator and the detector so as to obtain a plurality of images of an embowed part of the specimen based on the detected transmission X-ray. The synthesizer is configured to synthesize the plurality of images and output a synthesized image as an embowed part image. The processor is configured to determine a smooth line along the embowed part in the embowed part image. The calculator is configured to calculate a bow scale of the embowed part based on the smooth line.  
           [0017]    According to a seventh aspect of the present invention, there is provided a method of measuring a predetermined part in an X-ray image resulting from an X-ray diagnosis apparatus. The method comprises steps of generating an X-ray by a generator, detecting, by a detector, a transmission X-ray transmitted from a specimen resulting from exposure of the X-ray to the specimen, moving the generator and the detector so as to obtain a plurality of images of an embowed part of the specimen based on the detected transmission X-ray, synthesizing the plurality of images, outputting a synthesized image as an embowed part image, determining a smooth line along the embowed part in the embowed part image, and calculating a bow scale of the embowed part based on the smooth line. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    A more complete appreciation of embodiments of the present invention and many of its attendant advantages will be readily obtained by reference to the following detailed description considered in connection with the accompanying drawings, in which:  
         [0019]    [0019]FIG. 1 is an illustration showing examples of measuring techniques of a bow scale in a diagnosis of scoliosis according to a prior art of the present invention;  
         [0020]    [0020]FIG. 2 is a block diagram showing an exemplary configuration of an X-ray diagnosis apparatus including a medical image processor according to a first embodiment of the present invention;  
         [0021]    [0021]FIG. 3 is a block diagram showing an exemplary configuration of a medical image processor according to the first embodiment of the present invention;  
         [0022]    [0022]FIG. 4 is a flowchart showing an example of procedures of obtaining images on a spine of a specimen according to the first embodiment of the present invention;  
         [0023]    [0023]FIG. 5 is a flowchart showing an example of procedures of synthesizing vertebrae images so as to produce a synthesized spine image according to the first embodiment of the present;  
         [0024]    [0024]FIG. 6 is a flowchart showing an example of procedures of a Cobb angle calculation according to the first embodiment of the present invention;  
         [0025]    [0025]FIG. 7 is an illustration showing an example of a manual spine line and an example of a smooth spine line drawn in the synthesized spine image displayed in a display according to the first embodiment of the present invention;  
         [0026]    [0026]FIG. 8 is an illustration showing an example of the Cobb angle calculation according to the first embodiment of the present invention;  
         [0027]    [0027]FIG. 9 is an illustration showing an example of graphic data regarding the Cobb angle according to the first embodiment of the present invention;  
         [0028]    [0028]FIG. 10 is a flowchart showing an example of procedures of a ‘Vertical-alignment’ distance calculation according to the first embodiment of the present invention;  
         [0029]    [0029]FIG. 11 is an illustration showing an example of the ‘Vertical-alignment’ distance calculation according to the first embodiment of the present invention;  
         [0030]    [0030]FIG. 12 is a flowchart showing an example of procedures of an automatic spine line drawing according to a second embodiment of the present invention;  
         [0031]    [0031]FIG. 13 is an illustration showing an example of processes of the automatic spine line drawing according to the second embodiment of the present invention;  
         [0032]    [0032]FIG. 14 is an illustration showing another example of the Cobb angle calculation according to a third embodiment of the present invention;  
         [0033]    [0033]FIG. 15 is an illustration showing an example of image displays according to embodiments of the present invention; and  
         [0034]    [0034]FIG. 16 is an illustration showing an example of synthesized spine images shown from different directions according to embodiments of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0035]    Embodiments of the present invention will be described with reference to the accompanying drawings. In the embodiments of the present invention, it will be described that an X-ray diagnosis apparatus including a medical image processor may make it possible to accurately measure, as a bow scale, a bow angle of a spine and a deviant distance from a median line due to a bow of the spine. Embodiments of the present invention will be described using an example scoliosis measurement. Embodiments, however, of the present invention may not be limited to scoliosis, but may also be applied to cases, such as, for example, kyphosis, lordosis, bow legs, and any other defectiveness of bones, if it is applicable.  
         [0036]    (First Embodiment)  
         [0037]    [0037]FIG. 2 is a block diagram showing an exemplary configuration of an X-ray diagnosis apparatus including a medical image processor according to a first embodiment of the present invention. An X-ray diagnosis apparatus  20  may include a radiography equipment  21 , a high-voltage generator  22 , a mechanism controller  23 , a system controller  24 , a console  25 , and a medical image processor  26 . The radiography equipment  21  performs an X-ray radiography against a specimen P. The high-voltage generator  22  generates high-voltages which are necessary for the radiography equipment  21  to radiate an X-ray. The mechanism controller  23  controls a mechanism section of the radiography equipment  21  in response to designation signals from the console  25 . The system controller  24  performs overall controls for the X-ray diagnosis apparatus  20  including, particularly, the radiography equipment  21 , the high-voltage generator  22 , and the mechanism controller  23 . The console  25  provides various components of the X-ray diagnosis apparatus with designation signals. The medical image processor  26  analyzes and processes images obtained in the radiography equipment  21 .  
         [0038]    The radiography equipment  21  may be divided into three sections. The three sections may be called an X-ray generating section, an X-ray detecting section, and the mechanism section which moves the X-ray generating section and the X-ray detecting section, respectively.  
         [0039]    The X-ray generating section of the radiography equipment  21  may include an X-ray tube  211  and a collimator  212 . The X-ray tube  211  radiates (or generates) an X-ray to the specimen P. The collimator  212  collimates the X-ray radiated from the X-ray tube  211 . In detail, the X-ray tube  211  comprises a vacuum bulb. In the vacuum bulb, electrons are accelerated with high voltages supplied by the high-voltage generator  22  and are collided with a Tungsten target. Accordingly, the X-ray is generated from the vacuum bulb. The collimator  212  is provided between the X-ray tube  211  and the specimen P. The collimator  212  narrows down the X-ray radiated from the X-ray tube  211  for a predetermined image reception size so as to provide a clear image.  
         [0040]    The X-ray detecting section of the radiography equipment  21  may include an X-ray image intensifier (hereinafter referred to as an I.I.)  213  and an X-ray TV camera  214 . The X-ray radiated from the X-ray tube  211  is exposed to the specimen P through the collimator  212  and is transmitted from the specimen P as a transmission X-ray. The I.I.  213  receives the transmission X-ray and transforms the transmission X-ray to optical images. The TV camera  214  converts the optical images into electronic signals (or video signals). The electronic signals are output to the medical image processor  26 . The X-ray generating section and the X-ray detecting section are connected and supported by a supporter  215 . The X-ray generating section, the X-ray detecting section, and the supporter  215  are hereinafter called a radiography system.  
         [0041]    The mechanism section may include a movement mechanism  216  and a mechanism position detector  217 . The mechanism section is controlled by the mechanism controller  23  which may be provided outside the radiography equipment  21 . The movement mechanism  216  moves the radiography system along the body axis of the specimen P. The mechanism position detector  217  detects a position of the radiography system by counting the number of pulses output from an encoder furnished with the movement mechanism  216 . In addition, the mechanism position detector  217  outputs detection information to an external unit and also drives the high-voltage generator  22  so as to make the X-ray tube  211  radiate the X-ray.  
         [0042]    The radiography equipment  21  further includes a bed  218 . The bed  218  is usually a table supporting the specimen P during the radiography. The bed  218  may be made of materials which easily allow the X-ray to transmit the bed  218 . Generally, the radiography is implemented for the specimen P in an erect position which gives a force of gravity against the specimen P in a diagnosis of the scoliosis. Therefore, the bed  218  may be used as a footrest for the specimen P, as shown in FIG. 2.  
         [0043]    The high-voltage generator  22  generates high-voltages to be supplied to the X-ray tube  211  and to be impressed between an anode and a cathode of the X-ray tube  211  so as to accelerate thermal electrons. The thermal electrons are generated from the cathode of the X-ray tube  211 . The high-voltage generator  22  is capable of a large power, for example, 80 KW to 100KW, by an inverter system. The high-voltage generator  22  may also include an interface for informing the medical image processor  26  about timings of image data acquisition.  
         [0044]    The mechanism controller  23  controls the movement mechanism  216  based on designation signals from the console  25  through the system controller  24 . The mechanism controller  23  may control a moving speed and/or a moving direction of the radiography system along the body axis of the specimen P.  
         [0045]    The system controller  24  performs overall controls for the X-ray diagnosis apparatus  20  including controls of the image data acquisition and the mechanism movement based on the designation signals from the console  25 . The system controller  24  further includes controls of transferring acquired image data to the medical image processor  26 .  
         [0046]    The console  25  includes various switches and buttons, a keyboard, and a display panel. The console  25  may be operated by an operator, such as a doctor or a radiological technologist. Operations by the operator may include designations of radiography conditions and of movement of the mechanism section. The designation signals based on such operations are sent to each unit or component of the X-ray diagnosis apparatus  20  through the system controller  24 .  
         [0047]    The medical image processor  26  may include an image analyzer  261 , a mouse  262 , and a display  263 . The image analyzer  261  synthesizes (or combines) a plurality of image data acquired in the radiography system and calculates Cobb angles, ‘Vertical-alignment’ distances, and/or the like based on synthesized image data. The mouse is connected to the image analyzer  261  and is operative, by the operator, to input to the image analyzer  261  information necessary for the image calculation. The display  263  displays a synthesized image and calculation results. The detail of the medical image processor  26  will be described with reference to FIG. 3.  
         [0048]    According to the first embodiment and also the following embodiments of the present invention, the medical image processor  26  will be described as a part of the X-ray diagnosis apparatus  20 . Embodiments of the present invention, however, may not be limited to such a use of the medical image processor. The medical image processor may be used as an independent medical image processing apparatus according to embodiments of the present invention. For example, the independent medical image processing apparatus may be connected to one or more medical image equipments such as X-ray diagnosis apparatuses through a network. Further, the independent medical image processing apparatus may be provided in a place remote from an X-ray diagnosis apparatus without the medical image processor  26 . The remote place can be, for example, a different room, a different floor, a different hospital, a doctor&#39;s home, or any other medical facility. Still further, the medical image processor  26  or its processing features may also be installed in a workstation for interpreting medical images or in any other computerized equipment with or without features for specific purposes. In any cases, the medical image processor or the medical image processing apparatus may process images obtained through a network or images obtained from a storage media as off-line data.  
         [0049]    [0049]FIG. 3 is a block diagram showing an exemplary configuration of the medical image processor  26  according to the first embodiment of the present invention. FIG. 3 also shows external equipments, such as an image workstation and a laser imager, which can be connected to the medical image processor  26  (the X-ray diagnosis apparatus  20 ).  
         [0050]    The image analyzer  261  may comprise a memory section, a calculation section, and an interface section.  
         [0051]    The memory section of the image analyzer  261  may include an image memory  2611 , an image position information memory  2612 , a synthesized image memory  2613 , a graphic data memory  2614 , a calculation result memory  2615 , and a hard disk  2616 . The image memory  2611  stores the plurality of image data of the specimen P. The image position information memory  2612  stores position information of the image data stored in the image memory  2611 . In other words, the image position information memory  2612  stores information regarding the position of the specimen when each image data have been acquired. The synthesized image memory  2613  stores the synthesized image data. The graphic data memory  2614  stores graphic data (or overlay data). The calculation result memory  2615  stores a result of calculations of the Cobb angles and the ‘Vertical-alignment’ distances. The hard disk  2616  stores information or data, such as the synthesized image data, the graphic data, and the result of calculations.  
         [0052]    The calculation section of the image analyzer  261  may include an image synthesizer  2617  and a CPU (Central Processing Unit)  2618 . The image synthesizer  2617  synthesizes the plurality of image data stored in the image memory  2611  in accordance with the position information stored in the image position information memory  2612  and outputs the synthesized image data to the synthesized image memory  2613 . The CPU  2618  calculates the Cobb angles and/or the ‘Vertical-alignment’ distances based on the synthesized image data, and outputs a result of the calculations to the calculation result memory  2615 .  
         [0053]    The interface section of the image analyzer  261  may include a display interface  2619 , an operation input interface  2620 , and a communication interface  2621 . The display interface  2619  interfaces for displaying a synthesized image, the graphic data, the result of calculation, and/or the like in the display  263 . The display interface  2619  may further add or synthesize the synthesized image data with the graphic data and further with the result of calculation. The operation input interface  2620  interfaces, for example, a connection with the mouse  262 . The communication interface  2621  interfaces a connection with an external equipment  30 , such as, for example, a workstation  31  and a laser imager  32 .  
         [0054]    The display  263  displays data and information stored in the synthesized image memory  2613 , the graphic data memory  2614 , the calculation result memory  2615 , and/or the hard disk  2616 , through the display interface  2620 .  
         [0055]    The mouse  262  may be used as an input device, interactively responding to various menu displayed in the display  263 . In addition, the mouse  262  may also be used for manually tracing the spine displayed as a part of the synthesized image and for setting a range of pattern recognition according to embodiments of the present invention. The tracing and the pattern recognition will be described later.  
         [0056]    In the following description, components of the image analyzer  261  will be further explained in more detail.  
         [0057]    The image memory  2611  may be a semiconductor memory for the plurality of image data (transmission image data) radiographed while the radiography system is moving along the body axis of the specimen P. The image data may be stored in the image memory  2611  in a form of electronic (or video) signals converted into digital signals in the X-ray TV camera  214 . The image position information memory  2612  stores each position of the radiography system detected by the mechanism position detector  217  when each of the plurality of image data is acquired. In other words, each position information of the plurality of image data is stored in the image position information memory  2612 .  
         [0058]    The image synthesizer  2617  produces the synthesized image data by synthesizing (or combining) the plurality of image data stored in the image memory  2611  based on the position information of the plurality of image data from the image position information memory  2612 . The synthesized image data are output to and stored in the synthesized image memory  2613 . Further, the graphic data memory  2614  stores, as graphic data, construction or drawing information (including lines, curves, characters, and the like), which are presented based on drawing instructions by the mouse  262  or calculation results in the CPU  2618 . The calculation results are stored in the calculation result memory  2615 .  
         [0059]    The CPU  2618  is a primary computing unit which sets or determines a spine line based on the construction or the drawing information presented by the operator against the synthesized image displayed in the display  263  and stored in the graphic data memory  2614 . Further, the CPU  2618  calculates the Cobb angles and the ‘Vertical-alignment’ distances based on the construction or the drawing information presented by the operator on the synthesized image displayed in the display  263  and stored in the graphic data memory  2614 .  
         [0060]    The hard disk  2616  is a device to store the synthesized image data, stored in the synthesized image memory  2613 , attending the image position information stored in the image position information memory  2612 , the construction or the drawing information (graphic data) stored in the graphic data memory  2614 , and the calculation results stored in the calculation result memory  2615 .  
         [0061]    The display interface  2619  reads out data from the synthesized image memory  2613 , the graphic data memory  2614 , the calculation result memory  2615 , and/or the hard disk  2616 . Further, the display interface  2619  converts the read-out data into data in a TV format so as to display the data in the display  263 . When the data are displayed in the display  263 , only the synthesized image may be displayed in the display  263  through the display interface  2619  in a predetermined first stage. In a predetermined second stage, the display interface  2619  synthesizes the synthesized image with the graphic data. In other words, the display interface  2619  prepares the synthesized image overlaid with the graphic data. The synthesized image overlaid with the graphic data are displayed in the display  263 . Similarly, in a predetermined third stage, the display interface  2619  further overlays the calculation results on the synthesized image already overlaid with the graphic data. Such synthesized image overlaid with the calculation results is displayed in the display  263 .  
         [0062]    The operation input interface  2620  interfaces the information from input devices (such as the mouse  262 ) for providing the medical image processor  26  with the information. The communication interface  2621  reads out data from the synthesized image memory  2613 , the graphic data memory  2614 , the calculation result memory  2615 , and/or the hard disk  2616 . Further, the communication interface  2621  interfaces a transfer of the read-out data to the external equipment  30 , such as the workstation  31  and the laser imager  32 . The workstation  31  may be a computerized-equipment usually used to interpret images for the purpose of image diagnosis. The laser imager  32  may be used to present images on a film.  
         [0063]    Next, processes of operations in the X-ray diagnosis apparatus will be explained with reference to FIGS.  2  to  5 , taking a synthesized image of the spine as an example of the first embodiment of the present invention. The human spine is usually known to comprise cervical vertebrae, thoracic vertebrae, lumbar vertebrae, sacral vertebrae, and coccygeal vertebrae. The cervical vertebrae comprise seven vertebrae. The thoracic vertebrae comprise twelve vertebrae. The lumbar vertebrae comprise five vertebrae. The sacral vertebrae comprise five vertebrae. The coccygeal vertebrae comprise three to five vertebrae, which configure a coccygeal bone. Each vertebra is connected to its adjacent vertebra through an intervertebral disk. Therefore, as it is well known, the spine can be curved. When, however, the spine is malfunctioned due to a disease or its growth under an abnormal circumstance, the spine may sometimes be shaped irregularly. Such irregularity may have to be properly diagnosed and be cured.  
         [0064]    [0064]FIG. 4 is a flowchart showing an example of procedures of obtaining images on the spine of the specimen P according to the first embodiment of the present invention. FIG. 5 is a flowchart showing an example of procedures of synthesizing vertebrae images so as to produce a synthesized spine image according to the first embodiment of the present invention.  
         [0065]    In the following procedures, the radiography may be performed over a range between a first cervical vertebra and a head of femur by moving the radiography system. Accordingly, images of vertebrae can be acquired through the spine.  
         [0066]    1. Radiography and storage of a plurality of image data  
         [0067]    Prior to the radiography, radiographic conditions are set with the console  25  by the operator. For example, when the radiography is going to be made at positions X 1 , X 2 , . . . , and XN with intervals of Δ X, these N points are set by the console  25 . The information of these N points may be sent to the mechanism position detector  217  through the system controller  24  and the mechanism controller  23 . The information may be then stored in a memory provided in the mechanism position detector  217  (step S 0 ). Responsive to the information, the mechanism controller  23  controls the radiography system to move to an initial position X 1  where the radiography is initiated (step S 1 ). The initial position X 1  may be adjacent to the first cervical vertebra.  
         [0068]    When a radiograph initiation instruction is given by the console  25  and is provided to the system controller  24 , the mechanism position detector  217  generates initial pulses at the initial position X 1 . The high-voltage generator  22  is driven responsive to the initial pulses. Further, an output of the high-voltage generator  22  drives the X-ray tube  211 , and accordingly X-ray pulses are radiated from the X-ray tube  211  and is exposed to the specimen P. This initial exposure may be at the initial position nearby the first cervical vertebra. A transmission X-ray transmitted from the specimen P is received and formed as an initial vertebrae image by the I.I.  213  and is further converted into digitized electronic signals by the X-ray TV camera  214  (step S 2 ). The digitized electronic signals-from the X-ray TV camera  214  are sent to the image analyzer  261  of the medical image processor  26  and stored in the image memory  2611  as initial vertebrae image data (step S 3 ). In addition, an instruction for writing in the initial vertebrae image data is sent to the image memory  2611  from the X-ray TV camera  214  in parallel with sending the initial vertebrae image data.  
         [0069]    At more or less the same time as the initial vertebrae image data are stored in the image memory  2611 , the mechanism position detector  217  outputs signals representing the initial position X 1  of the radiography system. The signals are sent to the image analyzer  261  and stored in the image position information memory  2612  of the image analyzer  261  (steps S 4  and S 5 ).  
         [0070]    When the radiography is finished at the initial position X 1 , the mechanism controller  23  provides a servomotor of the movement mechanism  216  with driving signals. Accordingly, the radiography system starts to move at a constant speed along the body axis of the specimen P (step S 6 ). Pulses output from the encoder in the radiography system are sent to the mechanism position detector  217 . A counter of the mechanism position detector  217  counts the number of the pulses output from the encoder. When the radiography system has moved a distance Δ X, an output of the counter corresponds to data representing a second position X 2 . Then, the mechanism position detector  217  sends pulses to the high-voltage generator  22  (step S 7 ). In a similar manner to the case of the initial position X 1 , the radiography system radiographs at the second position X 2 . Accordingly, second vertebrae image data are acquired and stored in the image memory  2611 . Also the mechanism position detector  217  outputs signals representing the second position X 2  of the radiography system. The signals are stored in the image position information memory  2612 .  
         [0071]    After the radiography at the second position X 2 , the radiography is repeated until a final position XN of the radiography system in a manner similar to the above description (step S 8 ). As a result, the radiography system moves from the position of the first cervical vertebra (the initial position X 1 ) to the position of the head of femur (the final position XN) at the constant speed along the body axis of the specimen P. In accordance with the movement of the radiography system, every time when an integrated value indicated by output pulses of the encoder in the radiography system corresponds to every data representing positions X 1 , X 2 , . . . , and XN, the radiography is implemented by the radiography system. The acquired image data (the initial vertebrae image data to a final vertebrae image data) are stored in the image memory  2611 . The position information (signals representing the initial position X 1  to the final position XN) is stored in the image position information memory  2612 . The acquired image data and/or the position information may also be stored in the hard disk  2616 . When the image data have been acquired at the positions X 1  to XN, the radiography is terminated (step S 9 ).  
         [0072]    2. Production and storage of a synthesized spine image  
         [0073]    When the radiography has been completed at the N positions and is terminated, the operator may use the mouse  262  and select a command icon displayed in the display  263 , which instructs to produce a synthesized spine image (step S 10 ). Responsive to the command selection, the vertebrae image data (the initial vertebrae image data to the final vertebrae image data) are read out from the image memory  2611  to the image synthesizer  2617  (step S 11 ). Then (alternatively before the step S 11 ) the position information of the initial position X 1  to the final position XN is read out from the image position information memory  2612  to the image synthesizer  2617  (step S 12 ).  
         [0074]    In the image synthesizer  2617 , the vertebrae image data are combined one to the next in accordance with the position information under controls of the CPU  2618 . For example, the initial vertebrae image data acquired at the initial position X 1  can be followed by the second vertebrae image data acquired at the second position X 2 . The second vertebrae image data acquired at the second position X 2  can be followed by the third vertebrae image data acquired at the third position X 3 . In a similar manner, all the vertebrae image data is sequentially combined through until the final vertebrae image data XN (step S 13 ). Image data resulting from the combination of the initial to the final vertebrae image data are stored as synthesized spine image data in the synthesized image memory  2613 . In detail, each vertebrae image data are sequentially written in the synthesized image memory  2613  in accordance with each write initiation address obtained by reducing each of the position information (i.e. each moved distance of the radiography system) into the number of pixels of the synthesized image memory  2613  (step S 14 ). The synthesized spine image data may be formatted in the display interface  2619  and displayed as a synthesized spine image in the display  263  (step S 15 ).  
         [0075]    After the completion of producing the synthesized spine image data (step S 16 ), the medical image processor  26  awaits calculation instructions of either the Cobb angles or the ‘Vertical-alignment’ distances (step S 17 ). If a calculation of the Cobb angles is instructed responsive to an operator&#39;s selection of a Cobb angle calculation command icon displayed in the display  263 , the procedures will follow a flowchart shown in FIG. 6. Alternatively, if a calculation of the ‘Vertical-alignment’ distance is instructed responsive to an operator&#39;s selection of a ‘Vertical alignment’ distance calculation command icon displayed in the display  263 , the procedures will follow a flowchart shown in FIG. 10.  
         [0076]    3. Calculation of the Cobb angle  
         [0077]    Procedures of a Cobb angle calculation will be described with reference to FIG. 6. FIG. 6 is a flowchart showing an example of procedures of the Cobb angle calculation according to the first embodiment of the present invention.  
         [0078]    When the operator selects the Cobb angle calculation command icon displayed in the display  263  by using the mouse  262 , the Cobb angle calculation is instructed responsive to the operator&#39;s selection. The medical image processor  26  prepares to start procedures of the Cobb angle calculation (step S 20 ).  
         [0079]    First of all, a spine line is drawn along the spine displayed in the synthesized spine image by the operator. The operator may manually try to draw the spine line along a center of the spine based on his or her sense. The spine line mentioned above is hereinafter referred to as a manual spine line. To draw the manual spine line, the operator may use the mouse  262  and place a cursor of the mouse  262  around a center position of the first cervical vertebra in the synthesized spine image displayed in the display  263 . After the operator has determined the cursor position, the operator may click at the cursor position and drag the cursor until a position around the head of femur, trying to keep a center of the spine (step S 21 ). This manual spine line (the track of the drawing) is stored in the graphic data memory  2614  and also in the calculation result memory  2615 . In addition, the manual spine line is overlaid on the synthesized spine image data in the display interface  2619 . Accordingly, the manual spine line is displayed with the synthesized spine image in the display  263  in real time.  
         [0080]    When the operator has completed drawing the manual spine line against the spine in the synthesized spine image displayed in the display  263 , he or she may instruct the completeness of the drawing by the mouse  262 . Accordingly, signals indicating the completeness are supplied to the CPU  2618  through the mouse  262  (step S 22 ). Responsive to the signals from the mouse  262 , the CPU  2618  interpolates and also smoothes the manual spine line. The interpolation and smoothing processing may be accomplished by conventional techniques. Accordingly, a smooth spine line may be obtained (step S 23 ).  
         [0081]    [0081]FIG. 7 is an illustration showing an example of the manual spine line and an example of the smooth spine line drawn in the synthesized spine image displayed in the display  262  according to the first embodiment of the present invention. FIG. 7 (A) shows the example of the manual spine line drawn by the operator. FIG. 7(B) shows the example of the smooth spine line, which has already been interpolated and smoothed in the CPU  2618 . It may be possible to balance out errors caused by the manual operation in the smoothing processing. The smooth spine line data are stored in the graphic data memory  2614  and the calculation result memory  2615  (step S 24 ). In addition, the smooth spine line is displayed in the display  263 . In the display  263 , the manual spine line may be replaced with the smooth spine line in response to the processing by the CPU  2618 . Alternatively, both the manual spine line and the smooth spine line may be displayed side by side.  
         [0082]    When the interpolation and smoothing processing has been completed, the CPU  2618  automatically calculates the Cobb angles based on the smooth spine line data stored in the graphic data memory  2614  and the calculation result memory  2615 . In the Cobb angle calculation, the CPU  2618  calculates gradients (or angles), against a horizontal line, of perpendicular lines perpendicular to tangent lines at predetermined points on the smooth spine line. As a result, the CPU  2618  obtains perpendicular lines, which have the greatest gradients (angles).  
         [0083]    The Cobb angle calculation will be described in more detail with reference to FIG. 8. FIG. 8 is an illustration showing an example of the Cobb angle calculation according to the first embodiment of the present invention. The CPU  2618  calculates primary differentials at predetermined points on the smooth spine line and obtains tangent lines at the predetermined points (step S 25 ). The predetermined points may be determined at predetermined intervals on the smooth spine line, depending on, for example, the resolution of the display  263  or the information included in the smooth spine line data. Next, the CPU  2618  obtains perpendicular lines perpendicular to the tangent lines, respectively. When the perpendicular lines are obtained, the CPU  2618  calculates gradients of the perpendicular lines. In other words, the CPU  2618  calculates angles between a horizontal line and the perpendicular lines. The gradients (and/or angles) may be stored in the calculation result memory  2615  (step S 26 ).  
         [0084]    When the gradients of all the perpendicular lines have been obtained, the CPU  2618  divides the smooth spine line into two or more zones in accordance with signs of the gradients. As shown in FIG. 8, a sign of the gradients above a y-coordinate Y 2  along the Y-axis is positive. Therefore, this part of a smooth spine line  80  may be categorized as a zone  1 . At coordinates (X 2 , Y 2 ) and (X 1 , Y 1 ), the gradients become zero (0). Further, a sign of the gradients between y-coordinates Y 2  and Y 1  is negative. Therefore, this part of the smooth spine line  80  may be categorized as a zone  2 . Similarly, since a sign of the gradients is positive again below a y-coordinate Y 1 , this part of the smooth spine line  80  may be categorized as a zone  3  (step S 27 ).  
         [0085]    After the determination of the zones, the CPU  2618  selects one of the perpendicular lines perpendicular to the tangent lines at the predetermined points on the part of the smooth spine line  80 , which belongs to the zone  1 . The one perpendicular line to be selected can be a perpendicular line with a greatest gradient in the zone  1 . In FIG. 8, for example, a perpendicular line  81  is selected. The perpendicular line  81  is perpendicular to a tangent line  82  at a tangent point a 1  on the smooth spine line  80 . The perpendicular line  81  produces an angle θ  1  against a horizontal line  83 . At a tangent point (X 2 , Y 2 ), a gradient of a perpendicular line (not shown) perpendicular to a tangent line  84  becomes zero as mentioned above. Regarding the zone  2 , the CPU  2618  also selects one of the perpendicular lines perpendicular to the tangent lines at the predetermined points on the part of the smooth spine line  80 , which belongs to the zone  2 . The one perpendicular line to be selected can be a perpendicular line with a greatest gradient in the zone  2 . Again in FIG. 8, for example, a perpendicular line  85  is selected. The perpendicular line  85  is perpendicular to a tangent line  86  at a tangent point a 2  on the smooth spine line  80 . The perpendicular line  85  produces an angle θ  2  against a horizontal line  87 . At a tangent point (X 1 , Y 1 ), a gradient of a perpendicular line (not shown) perpendicular to a tangent line  88  becomes zero as mentioned above. Still further, in the zone  3 , the CPU  2618  still selects one of the perpendicular lines perpendicular to the tangent lines at the predetermined points on the part of the smooth spine line  80 , which belongs to the zone  3 . The one perpendicular line to be selected can be a perpendicular line with a greatest gradient in the zone  3 . Again in FIG. 8, for example, a perpendicular line  89  is selected. The perpendicular line  89  is perpendicular to a tangent line  90  at a tangent point a 3  on the smooth spine line  80 . The perpendicular line  89  produces an angle θ  3  against a horizontal line  91  (step S 28 ).  
         [0086]    With those angles θ  1  to θ  3 , the CPU  2618  calculates the Cobb angles. A first Cobb angle α is obtained by adding an absolute angle of the angle θ  1  and an absolute angle of the angle θ  2 . Similarly, a second Cobb angle β is obtained by adding an absolute angle of the angle θ  2  and an absolute angle of the angle θ  3  (step S 29 ). These Cobb angle data may be stored in the calculation result memory  2615 . Also graphic data including the angles α and β as shown in FIG. 9 may be stored in the graphic data memory  2614  (step S 30 ). In addition to the storage, the graphic data stored in step S 30  may be overlaid on smooth spine image data in the display interface  2619 . Accordingly, the smooth spine image with the Cobb angle information can be displayed in the display  263 . Information regarding the Cobb angle calculation including the Cobb angles and the gradients of the perpendicular lines may be stored as calculation result data in the hard disk  2616  as well as the calculation result memory  2615  (step S 31 ).  
         [0087]    4. Calculation of the ‘Vertical-alignment’ distance  
         [0088]    Procedures of a ‘Vertical-alignment’ distance calculation will be described with reference to FIG. 10. FIG. 10 is a flowchart showing an example of procedures of the ‘Vertical-alignment’ distance calculation according to the first embodiment of the present invention.  
         [0089]    As described in step S 17  of FIG. 5, while the medical image processor  26  awaits the calculation instructions, if the operator selects the ‘Vertical-alignment’ distance calculation command icon displayed in the display  263  by using the mouse  262 , the ‘Vertical-alignment’ distance calculation is instructed responsive to the operator&#39;s selection. The medical image processor  26  prepares to start procedures of the ‘Vertical-alignment’ distance calculation (step S 40 ).  
         [0090]    First of all, the CPU  2618  calibrates a relationship between a pixel of the synthesized spine image displayed in the display  263  and an actual distance of the spine of the specimen P. For example, radiography conditions may usually be set in advance of the radiography in accordance with operations in the console  25  by the operator. An expansion ratio of the image determined based on a physical inter-relationship among the X-ray tube  211 , the specimen P, and the I.I.  213  may also be set with other conditions at the time when the radiography conditions are set. The expansion ratio of the image can be understood as the number of pixels per a unit length of the image. Therefore, the number of pixels per a unit length of the synthesized spine image displayed in the display  263  may be obtained by performing corrections of expansion or reduction ratio for the synthesized spine image data stored in the synthesized image memory  2613 . Accordingly, a conversion ratio may be determined between a length in the display  263  and an actual length (step S 41 ).  
         [0091]    After the calibration in step S 41 , a spine line of the spine in the synthesized spine image is determined in a similar manner to the case of the Cobb angle calculation. The synthesized spine image stored in the synthesized image memory  2613  is displayed in the display  263  through the display interface  2619 . The operator may use the mouse  262  and place a cursor of the mouse  262  around a center position of the first cervical vertebra in the synthesized spine image displayed in the display  263 . After the operator has determined the cursor position, the operator may click at the cursor position and drag the cursor until a position around the head of femur, trying to keep a center of the spine (step S 21  in FIG. 6). When the operator has completed drawing a manual spine line against the spine in the synthesized spine image displayed in the display  263  (step S 22  in FIG. 6), the CPU  2618  interpolates and also smoothes the manual spine line. Accordingly, a smooth spine line may be obtained (step S 23  in FIG. 6). Smooth spine line data are stored in the graphic data memory  2614  and the calculation result memory  2615  (step S 24  in FIG. 6).  
         [0092]    [0092]FIG. 11 is an illustration showing an example of the ‘Vertical-alignment’ distance calculation according to the first embodiment of the present invention. When the smooth spine line data are obtained and overlaid on the synthesized spine image data, a smooth spine image may be displayed in the display  263 . With reference to the smooth spine image, the operator may try to draw a median line  110  against a smooth spine line  111  in the smooth spine image. The operator designates an original point  112  of the median line  110  by operating the mouse  262 , observing the smooth spine image displayed in the display  263 . Although it would be possible to set an original point at the coccygeal bone, which is situated at the bottom of the spine, it is likely to be difficult to recognize the coccygeal bone (coccygeal vertebrae) clearly due to the flatus. Therefore, in such a case, an original point may be set to a median point of a line segment to connect a left head of femur and a right head of femur. When the original point  112  has been designated (or determined), the CPU  2618  automatically draws a vertical line (i.e. the median line  110 ) from the original point  112 . The median line  110  and the original point  112  may be overlaid on the smooth spine image and displayed in the display  263  (step S 42 ). Once the original point  112  has been determined and the median line  110  has been drawn, the operator may then designate a terminal point  113  on the median line  110 , which specifically determines a range of the median line in the calculation (step S 43 ). For this designation, the operator may also use the mouse  262 .  
         [0093]    The CPU  2618  then calculates intersection points (X 0 , Y 3 ) and (X 0 , Y 2 ) where the median line  110  intersects with the smooth spine line  111  between the original point  112  (which is another intersection point (X 0 , Y 1 )) and the terminal point  113 . Accordingly, a range between the intersection point (X 0 , Y 1 ) (i.e. the original point  112 ) and the intersection point (X 0 , Y 2 ) may be categorized as a zone  6 . Another range between the intersection points (X 0 , Y 2 ) and (X 0 , Y 3 ) may be categorized as a zone  5 . Further, a range between the intersection point (X 0 , Y 3 ) and the terminal point  113  may be categorized as a zone  4  (step S 44 ). In an example shown in FIG. 11 (B), ‘Vertical-alignment’ distances are calculated in the zones  5  and  6 . When perpendicular line segments are dropped from the smooth spine line  111  to the median line  110 , the ‘Vertical-alignment’ distance can be defined as a distance of a longest one of the perpendicular line segments. In FIG. 11 (B), a perpendicular line segment  114  may be longest in the zone  6 . In the zone  5 , a perpendicular line segment  115  may be longest (step S 45 ). These perpendicular line segments  114  and  115  may or may not be displayed in the display  263 . Distances of the perpendicular line segments  114  and  116  are converted into actual distances (step S 46 ). Results of the above calculations may be stored in the calculation result memory  2615  and also displayed in the display  263  in a manner of overlaying on the smooth spine image (step S 47 ). Further, drawing information including one or more of the medial line  110 , the original point  112 , the terminal point  113 , and the perpendicular line segments  114  and  115  may be stored as graphic data in the graphic data memory  2614 . In addition to the above storage, in the hard disk  2616  stored may be the results of the calculation including a pixel, converted distances, distances of the perpendicular line segments  114  and  115 , positions on the smooth spine line  111  where the perpendicular line segments  114  and  115  are dropped, the original point  112 , and the terminal point  113  (step S 48 ).  
         [0094]    As an additional feature of the X-ray diagnosis apparatus  20 , the data stored in the hard disk  2616  including the smooth spine image data and its attendant data such as the graphic data and the result of the calculation may be transferred by transmission to the workstation  31  and/or the laser imager  32  (step S 49 ). Data to be transferred may alternatively be only the smooth spine image data. When the storage (and the transfer) has been completed, the calculation of the ‘Vertical-alignment’ distance may be terminated (step S 50 ).  
         [0095]    As described above, according to the first embodiment of the present invention, involvement of a human being system (the operator) may be reduced in the calculations of the Cobb angle and the ‘Vertical-alignment’ distance, compared to the prior art. This may result in improvement of the calculation accuracy and the reproducibility of the calculation result. Further, it may result in reduction of time required for obtaining the Cobb angle and the ‘Vertical-alignment’ distance.  
         [0096]    Although the first embodiment of the present invention has exemplary advantages mentioned above, the first embodiment of the present invention still includes the manual operation using the mouse  262  by the operator in the process of determining the spine line during the calculation procedures. Such calculation still relies on experiences and skills of the operator, which leaves a possibility of deteriorating the calculation accuracy when an inexperienced or unskilled operator is involved in the calculation. In the following description, another embodiment of the present invention will be described as a second embodiment of the present invention, which may reduce the possibility of the deterioration in the first embodiment of the present invention.  
         [0097]    (Second Embodiment)  
         [0098]    The second embodiment of the present invention will be described with reference to FIGS. 12 and 13. FIG. 12 is a flowchart showing an example of procedures of an automatic spine line drawing according to the second embodiment of the present invention. FIG.  13  is an illustration showing an example of processes of the automatic spine line drawing according to the second embodiment of the present invention. In the second embodiment of the present invention, the synthesized spine image stored in the synthesized image memory  2613  is displayed in the display  263  through the display interface  2619 . In the synthesized spine image, a representative point may be determined for each vertebra of the spine in the synthesized spine image. Every determined representative point may sequentially be connected by line segments. By smoothing the connected line segments, an automatically drawn spine line can be obtained. As one exemplary way of determining the representative points, each vertebra of the spine in the synthesized spine image displayed in the display  263  is recognized its outline as a square by a pattern recognition technique as shown in FIG. 13.  
         [0099]    In general, there are introduced many kinds of the pattern recognition techniques. One of popular pattern recognition techniques may be as follows: a differential processing is made for an object image; in the object image, ridge lines are traced for edges with a greatest value; and accordingly, information of a shape of the object can be obtained. In another popular technique of the pattern recognition, an original image is binarized, and then its binarized edge is traced.  
         [0100]    When the operator selects either the Cobb angle calculation command icon or the ‘Vertical-alignment’ distance calculation displayed in the display  263  by using the mouse  262 , the selected calculation is instructed responsive to the operator&#39;s selection. The medical image processor  26  prepares to start procedures of the selected calculation (step S 60 ).  
         [0101]    In the preparation for the following actual calculation of either the Cobb angle or the ‘Vertical-alignment’ distance, first of all, each selected vertebra of the spine in the synthesized spine image is extracted by the pattern recognition in the following steps  61  to  63 . For implementing the pattern recognition efficiently, a region  130  including two or more vertebrae of the spine may be designated as an object of the pattern recognition as shown in FIG. 13 (A). The designation may be accomplished by circumscribing such vertebrae, using the mouse  262  (step S 61 ). When the region for the pattern recognition has been designated, a histogram is prepared for the designated region of the synthesized spine image as shown in FIG. 13 (B). According to the histogram, a predetermined threshold  131  is set and applied to signals of the brightness so as to exclude the signals below the threshold  131 . Accordingly, a binarized image is prepared in the designated region  130  as shown in FIG. 13 (C). The CPU  2618  then performs a two-dimensional differential processing on the binarized image and extracts edges of the binarized image (i.e., edges of the vertebrae). The extracted edges may be corrected for its fractures in accordance with or referring to baseline data of a vertebra shape in the CPU  2618  (step S 63 ). Through the above steps S 61  to S 63 , each of the vertebrae in the designated region  130  may be recognized as a square as shown in FIG. 13 (D).  
         [0102]    After the pattern recognition of the vertebrae in the designated region  130  as a collective of a plurality of squares, a center of each of the squares (vertebrae) is calculated in the CPU  2618 . The center may be determined as an intersection point of diagonals (step S 64 ). Centers of each adjacent two of the squares (vertebrae) are connected in a line segment. Alternatively, it may be possible to connect centers of each vicinal two of the squares (vertebrae) as long as the accuracy is allowed. In other words, for example, every one or two of centers of squares (vertebrae) may be connected in a line segment. Accordingly, centers of the squares (vertebrae in the designated region) are connected in a line  132  as shown in FIG. 13 (E). The CPU  2618  interpolates and also smoothes the line  132 . Accordingly, an automatic smooth spine line may be obtained (step S 65 ). Smooth spine line data may be stored in the graphic data memory  2614 . Information regarding the calculation of the automatic smooth spine line may be stored in the calculation result memory  2615 .  
         [0103]    In the step S 64 , the center of the square (vertebra) has been determined as the intersection point of the diagonals. The center, however may be a gravity point of the square. Further, the designation of the region for the pattern recognition in step S 61  may alternatively be accomplished by manually drawing a manual preliminary spine line by the operator, using the mouse  262 . In this case, vertebrae on which the manual spine line has been drawn can be construed as objects for the pattern recognition.  
         [0104]    Upon obtaining the automatic smooth spine line, either designated one of the Cobb angle calculation or the ‘Vertical-alignment’ distance calculation may be performed on the basis of the automatic smooth spine line. The Cobb angle calculation and the ‘Vertical-alignment’ distance calculation may be implemented in a manner similar to the description made for the first embodiment of the present invention.  
         [0105]    According to the second embodiment of the present invention, a spine line is determined by the pattern recognition technique. In other words, the spine line is automatically calculated in the CPU  2618 . Therefore, it may be possible to reduce a resulting difference between operators and a problem of the reproducibility in the follow-up observation of the spine. As a result, it may be possible to improve the accuracy of the calculation. In addition, it may also make it possible to further reduce time required for obtaining the Cobb angle and the ‘Vertical-alignment’ distance since the time of drawing the manual spine line by the operator is not required. The operator may be relieved from manually drawing the manual spine line required in the first embodiment of the present invention.  
         [0106]    In the second embodiment of the present invention, the automatic smooth spine line has been obtained and used in the Cobb angle calculation and the ‘Vertical-alignment’ distance calculation. Regarding, however, the Cobb angle calculation, any type of the spine line may not be necessary for the calculation as long as each vertebra in the synthesized spine image is recognized in the pattern recognition.  
         [0107]    (Third Embodiment)  
         [0108]    A third embodiment of the present invention will be described with reference to FIG. 14. FIG. 14 is an illustration showing another example of the Cobb angle calculation according to the third embodiment of the present invention. In the third embodiment of the present invention, the Cobb angle calculation described in the second embodiment of the present invention may be improved in its efficiency. The improved calculation is also based on condition that outlines of vertebrae in the designated region of the synthesized spine image are extracted as a collective of a plurality of squares in the pattern recognition in a manner similar to the second embodiment of the present invention.  
         [0109]    For each of the extracted squares, the CPU  2618  draws a line segment (hereinafter referred to as an elongation) along an extension of an upper side of the each square. After the drawing, the CPU  2618  calculates gradients of the drawn elongations against a horizontal line (or angles between a horizontal line and the drawn elongations). In accordance with signs of the calculated gradients, the CPU  2618  divides the squares (vertebrae) into two or more zones. After the determination of the zones, the CPU  2618  selects one of elongations in each zone, which has a greatest gradient (angle) in the each zone. Further, the CPU  2618  calculates an angle between one elongation selected in a first zone and one elongation selected in a second zone adjacent to the first zone. The calculated angle can be construed as a Cobb angle. In this calculation, the CPU  2618  may simply add an angle between the horizontal line and the elongation selected in the first zone with an angle between the horizontal line and the elongation selected in the second zone.  
         [0110]    For example, in FIG. 14 (A), an elongation  140  is drawn along an upper side of a square (vertebra)  141  and selected as an elongation with a greatest gradient (angle γ  1 ) in a zone  7 . Similarly, an elongation  142  is drawn along an upper side of a square (vertebra)  143  and selected as an elongation with a greatest gradient (angle γ  2 ) in a zone  8 . The CPU  2618  adds the angle γ  1  with the angle γ  2  and obtains an angle γ as a Cobb angle.  
         [0111]    The calculation result which may include the gradients, the angles, the elongations including the selected elongations, and the like, may be stored in the calculation result memory  2615 . Further, the graphic data such as shown in FIG. 14 (A) may also be stored with the above mentioned calculation result in the graphic data memory  2614 . The graphic data with the calculation result stored in the graphic data memory  2614  are overlaid on the synthesized spine image data stored in the synthesized image memory  2613  in the display interface  2619 . Accordingly, the synthesized spine image with the Cobb angle calculation result is displayed in the display  263 . Still further, the calculated and/or obtained data stored or to be stored in the calculation result memory  2615  and/or the graphic data memory  2614  may also be stored as attendant data in the hard disk  2616 .  
         [0112]    [0112]FIG. 14 (A) shows an example of drawing elongations along an upper side of a square (vertebra). Elongations, however, are not limited to such an example. Elongations may also be drawn along a lower side of a square (vertebra). In addition, when the upper side of the square is not parallel with the lower side of the square, a gradient (angle) averaged between the gradient (angle) of the upper side and the gradient (angle) of the lower side of the square may be used as a gradient (angle) of an elongation for the square. Still further, as shown in FIG. 14 (B), an elongation  144  in the zone  7  may be determined as a line through a median point  145  of a left side of the square and a median point  146  of a right side of the square. Similarly, in the zone  8 , an elongation  147  may be determined as a line through a median point  148  of a left side of the square and a median point  149  of a right side of the square.  
         [0113]    [0113]FIG. 15 is an illustration showing an example of image displays according to embodiments of the present invention. In embodiments of the present invention, a synthesized spine image displayed in the display  263  may not be limited to the synthesized spine image shown from a front (e.g. FIG. 16 (A)) or from a back of the specimen P as shown in FIG. 15 (A). When a synthesized spine image shown from a right side or from a left side (e.g. FIG. 16 (B)) of the specimen P is obtained, such a synthesized spine image may be displayed in the display  263  as shown in FIG. 15 (B). Further, if both of these synthesized spine images are obtained, both of the images may be displayed side by side as shown in FIG. 15 (C). Alternatively, each of these images may be switched to be displayed independently.  
         [0114]    According to the above description, the synthesized spine image has been based on the images obtained from the X-ray diagnosis apparatus. Embodiments of the present invention may not be limited to this, but may be applied to images obtained from other medical image equipments, such as, for example, an X-ray CT apparatus and an MRI apparatus. Further, the determination and/or the calculation of the automatic (smooth) spine line, the calculation of the Cobb angle, and the calculation of the ‘Vertical-alignment’ distance according to embodiments of the present invention may be handled independently as methods of determination or calculation, respectively.  
         [0115]    Further, in the above-described embodiments of the present invention, the Cobb angle and the ‘Vertical-alignment’ distance have been described as the bow scale. The bow scale, however, may not be limited to those if there is an alternative bow scale to which embodiments of the present invention may be applicable.  
         [0116]    In other embodiments of the present invention, it is contemplated that the bed  218  may move along the body axis of the specimen P, instead of or in addition to movement of the radiography system.  
         [0117]    Additionally, when specific or nonspecific buttons are provided in the console  25 , instructions may be made from such buttons, instead of or in addition to the selection of command icons displayed in the display  262 .  
         [0118]    Still further, in the embodiments of the present invention, the X-ray diagnosis apparatus or the medical image processing apparatus may have a random access memory (RAM), which can receive and store computer programs and applications as computer readable instructions in a temporary and/or non-volatile state. The X-ray diagnosis apparatus or the medical image processing apparatus may further have a hard disk drive as part of the controller for reading from and writing to a hard disk, a magnetic disk drive for reading from and writing to a magnetic disk, and/or an optical disk drive for reading from and writing to an optical disk (such as a CD, CDR, CD-RW, DVD, or other optical device). Those skilled in the art will appreciate that one or more of such memory, drives, and their respective media are examples of a computer program product for storing computer readable instructions, which when executed, may implement an embodiment of the present invention.  
         [0119]    Accordingly, an apparatus, which does not incorporate features of embodiments of the present invention can benefit the features as long as the apparatus is equipped with a feature of reading and performing a computer readable program.  
         [0120]    The embodiments of the present invention described above are examples described only for making it easier to understand the present invention, and are not described for the limitation of the present invention. Consequently, each component and element disclosed in the embodiments of the present invention may be redesigned or modified to its equivalent within a scope of the present invention. Furthermore, any possible combination of such components and elements may be included in a scope of the present invention as long as an advantage similar to those obtained according to the above disclosure in the embodiments of the present invention is obtained.