Title of Invention: Image display apparatus, image display control method, and computer readable medium having an image display control program recorded therein Abstract: Specification is received regarding which structure identifying information, each corresponding to an anatomical structure, is specified as display target structure identifying information to be displayed with a display target image when displaying the display target image, in which the positions of each pixel correspond to positions within an original image. The position of the anatomical structure identified by the structure identifying information is specified, based on structure information, in which structure identifying information that identifies anatomical structures and structure position information that represents the positions of the anatomical structures within the original image are correlated, and the correspondence of positions between the original image and the display target image. The display target structure identifying information is displayed with the display target image such that a user can recognize that the anatomical structure identified by the display target structure identifying information is displayed at the specified position. Detailed Description: Part general_description_paragraphs: Part CROSS-REFERENCE TO RELATED APPLICATIONS: The present application claims priority from Japanese Patent Application No. 2008-107391, filed Apr. 17, 2008, the contents of which are herein incorporated by reference in their entirety. Part BACKGROUND OF THE INVENTION: 1. Field of the Invention The present invention is related to a technique for displaying images of subjects that include predetermined anatomical structures, along with information that identifies the anatomical structures. 2. Description of the Related Art There is a known technique for administering image analysis on diagnostic images obtained by MRI imaging that include spinal columns of humans (as disclosed in K. L. Weiss et al., “Automated Spine Survey Iterative Scan Technique”, Radiology, Vol. 239, No. 1, pp. 255-262, The Radiological Society of North America, 2006). In this technique, image analysis is administered to extract vertebral disks within the image. Then, symbols for identifying the vertebra (C1 through C7 for the first through seventh cervical vertebrae, T1 through T12 for the first through twelfth thoracic vertebrae, and L1 through L5 for the fifth through fifth lumbar vertebrae) are attached with respect to each of the extracted vertebral disks, and the symbols are displayed to overlap the vertebral disks in the diagnostic images. During diagnosis based on images of subjects, the positions of diseased portions may be expressed using positional relationships among the diseased portions, surrounding organs, and bones. In this case, physicians are enabled to better understand the positions of diseased portions compared to cases in which the positions of diseased portions are expressed by coordinates of the images, and diagnostic efficiency is improved. If the information that identifies all of the vertebral disks are displayed to overlap the diagnostic images as in the technique disclosed by K. L. Weiss et al., the positional relationships among diseased portions and the vertebral disks becomes easy to understand. However, a great number of pieces of identifying information are displayed within diagnostic images, which deteriorates the visibility of the portions of the images at which the vertebral disks are pictured, and acts as a barrier to diagnosis. Part SUMMARY OF THE INVENTION: The present invention has been developed in view of the foregoing circumstances. It is an object of the present invention to provide an image display apparatus, an image display control method, and a computer readable medium in which an image display control program is stored, that reduces the deterioration in visibility of diagnostic images during image diagnosis in cases that information that identifies predetermined anatomical structures within diagnostic images are displayed along with the diagnostic images. An image display apparatus of the present invention is characterized by comprising: image display means for displaying a two dimensional display target image, in which the positions of each pixel are enabled to correspond to positions within an original image that represents a subject in two or more dimensions, based on the original image; structure information obtaining means for obtaining structure information, in which structure identifying information that identifies each of a plurality of predetermined anatomical structures within the subject and structure position information that represents the positions of the anatomical structures within the original image are correlated; structure identifying information specifying means for receiving specification regarding which of the structure identifying information, each corresponding to an anatomical structure, is specified as display target structure identifying information to be displayed along with the display target image; and structure position specifying means for specifying the position of the anatomical structure, which is identified by the structure identifying information, within the display target image, based on the structure information and the correspondence of positions between the original image and the display target image; the image display means displaying the display target structure identifying information along with the display target image such that a user can visually recognize that the anatomical structure which is identified by the display target structure identifying information is displayed within the display target image at the position specified by the structure position specifying means. An image display control method of the present invention is a method for displaying a two dimensional display target image, in which the positions of each pixel are enabled to correspond to positions within an original image that represents a subject in two or more dimensions, based on the original image, characterized by comprising the steps of: obtaining structure information, in which structure identifying information that identifies each of a plurality of predetermined anatomical structures within the subject and structure position information that represents the positions of the anatomical structures within the original image are correlated; receiving specification regarding which of the structure identifying information, each corresponding to an anatomical structure, is specified as display target structure identifying information to be displayed along with the display target image; specifying the position of the anatomical structure, which is identified by the structure identifying information, within the display target image, based on the structure information and the correspondence of positions between the original image and the display target image; and displaying the display target structure identifying information along with the display target image such that a user can visually recognize that the anatomical structure which is identified by the display target structure identifying information is displayed within the display target image at the position specified by the structure position specifying step. A computer readable medium of the present invention is that on which a program that causes a computer to execute the image display control method of the present invention is recorded. Note that those who are skilled in the art would know that computer readable media are not limited to any specific type of device, and include, but are not limited to: floppy disks, CD's, RAM's, ROM's, hard disks, magnetic tapes, and internet downloads, in which computer instructions can be stored and/or transmitted. Transmission of the computer instructions through a network or through wireless transmission means is also within the scope of the present invention. Additionally, computer instructions include, but are not limited to: source, object, and executable code, and can be in any language, including higher level languages, assembly language, and machine language. Hereinafter, the details of the present invention will be described. The “display target image” may be any type of image, as long as the positions of each pixel therein are enabled to correspond to positions within the original image. As a specific example, the original image may be a three dimensional image constituted by an agglomeration of sectional images taken at a plurality of points along a structural axis that extends in a predetermined direction. In this case, the display target image may be a sectional image taken at one of the plurality of points. As another example, the original image may be a two dimensional image. In this case, the display target image may be the same image as the original image, or a portion which is cut out from the original image. It is preferable for bones to be employed as the “plurality of predetermined anatomical structures within the subject”. Specific examples of the “structure identifying information” include the names of the anatomical structures, numbers that represent the anatomical structures, and symbols that represent the anatomical structures. The correlation between the “structure identifying information . . . , and structure position information” is a “one to one” correspondence in the case that the original image is expressed in three dimensions or less. This is because a single anatomical structure is present at a single specific position in this case. However, in the case that the original image is a four dimensional image that represents a three dimensional video of a subject, there is a possibility that a single anatomical structure will be present at different positions along the temporal phase. Therefore, the correlation between the structure identifying information and structure position information may become a “one to many” correspondence. In this case, a single piece of structure identifying information may be correlated with the position of a single anatomical structure at each temporal phase of the original image. Then, information regarding the position of the anatomical structure at a temporal phase corresponding to the temporal phase of a display target image may be employed to specify the position of the anatomical structure within the display target image. The process for “specifying the position of the anatomical structure, which is identified by the structure identifying information, within the display target image, based on the structure information and the correspondence of positions between the original image and the display target image” assumes the following. Each pixel of the display target image is correlated to a specific position within the original image. Meanwhile, the position of each of the anatomical structures within the original image, which are identified by the structure identifying information, is specified by the structure position information. Therefore, it is assumed that the positions of the anatomical structures which are identified by the structure identifying information within the display target image are specifiable indirectly via the positional coordinate system of the original image. Accordingly, it is possible to specify the positions of the anatomical structures which are identified by the structure identifying information within the display target image by the indirect correlation. The “structure information” may be obtained by image analyzing processes that recognize the anatomical structures within the original image. Alternatively, the “structure information” may be obtained by a user who views a two dimensional image obtained from the original image and manually sets the positions of the anatomical structures within the image. In addition, the “structure information” may be label images that represent the structure identifying information and the structure position information within the original image. Here, a “label image” is a multiple valued image, in which a label value (structure identifying information), which is different for each anatomical structure, is added to the position and region (structure position information) of each of the anatomical structures within the original image. The specification of the “display target structure identifying information” may be specification of a structure group identifying information that specifies a group constituted by a plurality of anatomical structures. In this case, the pieces of structure identifying information that identify the plurality of anatomical structures included in the group are specified as the display target structure identifying information. Specific examples of structure group identifying information include: a “ribs” group that includes the first through twelfth left and right ribs; a “vertebral bones” group that includes the first through seventh cervical vertebrae, the first through twelfth thoracic vertebrae, and the first through fifth lumbar vertebrae; a “left ribs” group, and a “cervical vertebra” group. In the case that a structure group identifying information is specified, a representative structure identifying information to be displayed along with the display target image from among the plurality of pieces of structure identifying information, each of which identifies an anatomical structure included in a group, may be determined based on a predetermined rule. In this case, the image display means may display only the determined representative structure identifying information from among the structure identifying information of the plurality of anatomical structures that belong to the group along with the display target image. The predetermined rule may be defined by at least one of: the distribution of positions, which have been specified by the structure position specifying means, of the plurality of anatomical structures included in the group which is identified by the specified structure group identifying information within the target display image; the structure identifying information of the plurality of anatomical structures; and the type of the display target image. That is, it is preferable for the predetermined rule to be defined such that an optimal piece of structure identifying information is selected as the representative structure identifying information to be displayed along with the display target image, according to: which direction the sectional image, which is the display target image, is a view from (the type of the display target image); the anatomical structure which is the display target of the structure identifying information; and where in the display target image the anatomical structures identified by the structure identifying information are displayed (the distribution of positions of the anatomical structures). Specification may be received regarding whether only the representative structure identifying information is to be displayed along with the display target image, or the structure identifying information for all of the anatomical structures that belong to the group which is identified by the structure group identifying information is to be displayed. Specification may also be received regarding the display position of the display target structure identifying information. The specification regarding the display position may be received such that the display target structure identifying information is displayed in the vicinity of the anatomic structure which is identified by the display target structure identifying information. Here, the specific range of positions which is defined by the term “vicinity” may be a uniform range which is set in advance. Alternatively, the range may be determined according to the type of the anatomical structure which is identified by the display target structure identifying information or the like. It is preferable for the specification of the display target structure identifying information, whether only the representative structure identifying information is to be displayed, and the display position of the structure identifying information to be realized via a user interface for receiving specifications by selection from among a plurality of selectable options. The present invention displays a two dimensional display target image, in which the positions of each pixel are enabled to correspond to positions within an original image that represents a subject in two or more dimensions, based on the original image. Specification is received regarding which of the structure identifying information, each corresponding to an anatomical structure, is specified as display target structure identifying information to be displayed along with the display target image. The position of the anatomical structure, which is identified by the structure identifying information, within the display target image is specified, based on the structure information, in which structure identifying information that identifies each of a plurality of predetermined anatomical structures within the subject and structure position information that represents the positions of the anatomical structures within the original image are correlated, and the correspondence of positions between the original image and the display target image. The display target structure identifying information is displayed along with the display target image such that a user can visually recognize that the anatomical structure which is identified by the display target structure identifying information is displayed within the display target image at the specified position. Accordingly, only pieces of structure identifying information which are desired by the user are displayed along with the display target image, from among the plurality of pieces of structure identifying information corresponding to the plurality of anatomical structures. Therefore, deterioration in visibility of the display target image due to the structure identifying information being overlapped thereon and displayed can be reduced, while maintaining the ease with which the positions of the anatomical structures identified by the specified structure identifying information are understood. Part BEST MODE FOR CARRYING OUT THE INVENTION: Hereinafter, a process in which identifying information that identifies vertebral bones and ribs are displayed along with a display target axial tomographic image that constitutes a portion of a three dimensional original image obtained by CT or MRI will be described as an embodiment of the present invention, with reference to the attached drawings. Note that in the following description, the identifying information will be referred to as vertebral bone numbers and rib numbers. In cases that it is not particularly necessary to clearly distinguish between the two, they will simply be referred to as bone numbers. In the following description, the vertebral bone numbers will be referred to as first through seventh cervical vertebrae, first through twelfth thoracic vertebrae, first though fifth lumbar vertebrae. The ribs numbers will be referred to as first through twelfth left ribs, and first through twelfth right ribs. Alternatively, symbols such as C1 through C7, T1 through T12, and L1 through L5 may be employed for the vertebral bones. FIG. 1 is a diagram that schematically illustrates the construction of a medical information system, in which an image processing work station 2 is incorporated. As illustrated in FIG. 1, the system is constituted by: an imaging apparatus 1 (imaging modality 1) for medical images; the image processing work station 2; an image server 3; and an image database 4. The components of the system are connected via a network 19 such that they can communicate with each other. The image processing work station 2 and the image server 3 are controlled by programs which are installed from a recording medium such as a CD-ROM. Alternatively, the programs may be downloaded from the memory device of a server which is connected to the image processing work station 2 and the image server 3 via a network such as the Internet, and then installed in the image processing work station 2 and the image server 3. The imaging modality 1 includes an apparatus that generates image data that represents a subject by imaging the subject, and outputs the image data with information, such as examination information and patient information, attached thereto. The attached information is of a standardized format such as the DICOM format, or a format unique to the manufacturer of the imaging modality 1. Specific examples of the imaging modality 1 include: CT (Computed Tomography); MRI (Magnetic Resonance Imaging); PET (Positron Emission Tomography); and ultrasound imaging apparatuses. Note that in the present invention, the image data are three dimensional images obtained by CT, MRI and the like that represent subjects, and are constituted by an agglomeration of axial tomographic images having predetermined slice intervals and slice widths. The image processing work station 2 is a computer equipped with a processing apparatus, at least one high definition display, input devices such as a keyboard and a mouse, and a communications interface that communicates with the image server 3 and the like via the network 19. A software program that causes the vertebral bone numbers and/or the rib numbers to be displayed with a display target image is installed in the image processing work station. A software program that provides the functions of a general purpose DBMS (Data Base Management System) having comparatively high processing performance is installed in the image server 3. The image server 3 is also equipped with a high capacity storage that constitutes the image database 4. The storage may be: a high capacity hard disk device which is connected to the image server 3 via a data bus; an NAS (Network Attached Storage) which is connected to the network 19; or a disk device which is connected to an SAN (Storage Area Network). The image server 3 is also equipped with a communications interface for communicating with the imaging modality 1, the image processing work station 2 and the like via the network 19. The image server 3 receives image data that represent images imaged and obtained by the modality 1 and registers the image data to the image database 4. The image server 3 also extracts image data that matches search criteria input through the image processing workstation from among image data registered in the image database 4, and transmits the extracted image data to the image processing workstation 2. The network 19 is a local area network that connects various apparatuses within a hospital. However, in the case that an image reading work station is provided at a different hospital or clinic, the network 19 may be a network that connects local area networks of different hospitals via the Internet or via dedicated networks. In either case, it is desirable for the network 19 to be that which enables high speed transfer of image data, such as an optical fiber network. FIG. 2 is a diagram that illustrates the functions of the image display process, which is the embodiment of the present invention, from among the functions that the image processing work station 2 performs. As illustrated in FIG. 2, the image display process, which is the embodiment of the present invention, is realized by: an original image/bone information obtaining section 21; a bone number display setting receiving section 22; a display target image obtaining section 23; a bone position specifying section 24; a representative bone number determining section 25; and a display control section 26. Control of the determination of data to be processed by each processing section, control of the processing order of each processing section, and the like are performed by a control section 27 (not shown), which is realized by the main program of the image display control program of the present invention being executed. Note that in the present embodiment, information (examination ID and series ID) that specifies image data of a three dimensional image which is the target of processing is input as start parameters when the program is started up. The original image/bone information obtaining section 21 transmits a search request to the image server 3, using the examination ID and the series ID as search criteria. The image server 3 searches the image database in response to the search request and extracts image data Img0 (hereinafter, images and image data that represent images will be referred to with the same reference labels) that represents the three dimensional image which is the target of processing and is correlated to the examination ID and the series ID. Then, the image data Img0 is transmitted to the image processing work station 2. The original image/bone information obtaining section 21 receives the image data Img0, and stores it in a predetermined region of a hard disk of the image processing work station 2. The image data may be stored as a collection of image files, each representing an axial tomographic image that constitutes the three dimensional image. The three dimensional image data Img0 also includes attached information, such as: bone information BI that includes bone numbers BIDn (n is a suffix that identifies each bone) for vertebral bones and ribs within the image, and position information COn regarding the bones identified by the bone numbers (hereinafter, referred to as “original bone position information”); and slice numbers. Each of the processing sections are capable of obtaining information necessary to perform the processes assigned thereto. Here, the bone information BI is generated by a bone information generating section 31 in advance, and added to the three dimensional image data Img0 as attached information. That is, the bone information generating section 31 performs an image analyzing process on the three dimensional image data Img0, which is obtained by the image server 3 from the image database 4. The bone information generating section 31 detects vertebral bones and ribs within the image, recognizes the vertebral bone numbers and the rib numbers for each of the detected vertebral bones and ribs, attaches bone numbers BIDn and original bone position information COn regarding the bones identified by the bone numbers BIDn to the three dimensional image data Img0 as attached information, and stores the three dimensional image data Img0 and the attached information in the image database 4. Because the bones are three dimensional anatomical structures, the original bone position information COn is information that represents three dimensional regions. Note that an example of the image analyzing process will be described later as a supplemental description. The bone number display setting receiving section 22 provides a graphical user interface for receiving specification of bone numbers BIDu (hereinafter, referred to as display target bone numbers BIDu) to be displayed along with a display target image Img1 (to be described layer in the explanation of the display target image obtaining section 23), a display method DM for the display target bone numbers BIDu, and display positions DP of the display target bone numbers BIDu. FIG. 4 is a diagram that illustrates a bone number display setting screen, as an example of the graphical user interface. Check boxes and a list box for receiving selection of display target bone numbers for the display target bone numbers BIDu are displayed at the left side of the screen of FIG. 4. Selection of display target bone numbers BIDu is received by a user operating a mouse or the like to check a check box corresponding to bone numbers to be displayed. Note that three check boxes are provided, to enable selection of only “Vertebral Bones”, only “Ribs”, “Vertebral Bones” and “Ribs”, and only “Individual Settings”. Specifically, in the case that “Vertebral Bones” is selected, the bone numbers of all of the individual vertebral bones, that is, the first through seventh cervical vertebrae, the first through twelfth thoracic vertebrae, and the first through fifth lumbar vertebrae, are selected as display targets. In the case that “Ribs” is selected, the bone numbers of the left and right first through twelfth ribs are selected as display targets. In the case that “Individual Settings” is selected, selection of display target bone numbers BIDu is received by the user operating a mouse or the like to click on bone numbers that the user desires to be displayed, from among the bone numbers in the list box at the lower left of the screen. The selected bone numbers are highlighted and displayed. Note that it is possible for the user to select a plurality of bone numbers from within the list box. Radio buttons for receiving selection of the display method DM for the display target bone numbers BIDu selected in the manner described above are displayed at the upper right of the screen of FIG. 4. Selection of the display method DM is received by the user operating a mouse or the like to select either “Display All” or “Display Representative Bone Number Only”. Here, in the case that “Display All” is selected, if the bones corresponding to the display target bone numbers BIDu are present in the display target image Img1, the bone numbers are displayed along with the display target image Img1. On the other hand, in the case that “Display Representative Bone Number Only” is selected, a representative bone number BIDE is determined from among the display target bone numbers BIDU which have been selected as described above and which are present within the display target image Img1, based on a predetermined rule. The method by which the representative bone number BIDE is determined will be described later in the description of the process performed by the representative bone number determining section 25. Note that the display method DM may be set to be selectable only when “Vertebral Bones” and/or “ribs” are selected as the display target bone numbers BIDU. Radio buttons for receiving selection of the display position DP of the display target bone numbers BIDU selected as described above are displayed at the lower right of the screen of FIG. 4. Selection of the display position DP is received by the user operating a mouse or the like to click either of the radio buttons for “Display Near Target” and “Display at Upper Right of Image”. Here, in the case that “Display Near Target” is selected, bone numbers are displayed in the vicinities of bones which are identified thereby in the display target image Img1 (refer to FIG. 6). The method by which the specific display positions are determined will be described later in the description of the process performed by the display control section 26. On the other hand, in the case that “Display at Upper Right of Image” is selected, bone numbers are displayed at a fixed position at the upper right of the display target image Img1. The display target image obtaining section 23 obtains image data that represents an axial tomographic image corresponding to the slice number (m0), which has been input as a startup parameter, from the three dimensional original image data Img0 as the display target image Img1. At this time, correspondence information R0, 1 that represents what position within the three dimensional original image an arbitrary position within the axial tomographic image having the slice number m0 corresponds to is also obtained. In the present embodiment, a position (x1, y1) within the display target axial tomographic image corresponds to a position (x1, y1, m0) within the three dimensional original image. The bone position specifying section 24 specifies the positions of bones identified by the display target bone numbers BIDU within the display target image Img1, using the bone numbers BIDn and the original bone position information COn within the three dimensional original image Img0, the correspondence information R0, 1 between the three dimensional original image Img0 and the display target image Img1, and the display target bone numbers BIDU as inputs. The bone position specifying section 24 then outputs position information CDU (hereinafter, referred to as display bone position information CDU) that represents the specified positions. Specifically, first, the bone position specifying section 24 obtains display bone position information CDn, that represents the positions of each bone identified by the bone number information BIDn in the display target image Img1 that represents the axial tomographic image at slice number m0, based on the original bone position information COn of the three dimensional original image Img0 and the correspondence information R0, 1. That is, in the present embodiment, the display bone position information CDn is extracted from the original bone position information COn of the three dimensional original image Img0, at the slice number m0. Accordingly, display position information CDn does not exist for bones which are not present in the display target image Img1 in other words, bones for which the region represented by original position information COn does not include positions at slice number m0. Next, the bone position specifying section 24 specifies the display bone position information CDU of the bones identified by the display target bone numbers BIDU within the display target image Img1, based on the display target bone numbers BIDU and the display bone position information CDn for each of the bones. Here, the display position information CDn does not exist for bones which are identified by the display target bone numbers BIDU but are not present in the display target image Img1. Note that the bone position specifying section 24 may specify the display bone position information CDU of bones to be displayed, by obtaining the original bone position information COU of bones which are identified by the display target bone numbers BIDU, and then performing conversion of the original bone position information COU, using the correspondence information R0, 1. The representative bone number determining section 25 determines a representative bone number BIDE to be displayed along with the display target image Img1, in the case that “Display Representative Bone Number Only” is selected as the display method DM. The representative bone number determining section 25 determines the representative bone number BIDE based on a predetermined rule, using the display target image data Img1, the display target bone numbers BIDU, and the display bone position information CDU for bones which are identified by the display target bone numbers BIDU as inputs. The representative bone number determining section 25 outputs the representative bone number BIDE and display bone position information CDE for the bone identified by the representative bone number BIDE. Here, specific examples of the predetermined rule include: “in the case that the display target image Img1 is an axial tomographic image, and the display target bone numbers BIDU include all vertebral bones, the bone number for vertebra B1 which is displayed in the display target image Img1 is the representative bone number BIDE”; and “in the case that the display target image Img1 is an axial tomographic image, and the display target bone numbers BIDU include all ribs, the bone numbers for ribs B2 and B3 which are closest to the center point in the vertical direction of the display target image Img1 (the front to back direction of the subject) are designated as the representative bone numbers BIDE”, as illustrated in FIG. 5. In the case of the latter rule regarding the ribs, the representative bone number determining section 25 determines the display target bone number BIDU of a bone with display bone position information CDU having the least difference in position from a central position Y0 in the vertical direction of the display target image Img1 as the representative bone number BIDE. The display control section 26 causes the display target image Img1 to be displayed on a display screen, along with the display target bone numbers BIDU or the representative bone numbers BIDE at positions specified by the display position information DP. The display control section 26 uses the display target image data Img1, the display target bone numbers BIDU and the display bone position information CDU for the bones identified by the display target bone numbers BIDU, or the display target image data Img1, the representative bone numbers BIDE and the display bone position information CDE for the bones identified by the representative bone numbers BIDE as inputs. Here, even if bones are specified as display target bone numbers BIDU, if the bones are not present in the display target image Img1, display position information CDn does not exist for these bones. Therefore, the bone numbers corresponding to these bones are not displayed along with the display target image Img1. FIG. 6 is a diagram that illustrates an example of display in the case that “Display Near Target” is selected as the display positions DP. As illustrated in FIG. 6, the display control section 26 determines the display positions of each bone number, based on the display target bone numbers BIDU or the representative bone numbers BIDE and the display bone position information CDU or CDE corresponding thereto, according to a preset rule. An example of the preset rule is: “in the case that the display target image Img0 is an axial tomographic image, rib numbers are displayed to the exterior of the ribs represented by the rib numbers, and a vertebra number is displayed toward the lower right (or the lower left) of the vertebra represented by the vertebra number”. Then, the display control section 26 overlaps the display target bone numbers BIDU or the representative bone numbers BIDE onto the display target image Img1 and displays the display target image Img1. On the other hand, in the case that “Display at Upper Right of Image” is selected as the display position DP, overlapped display such as that illustrated in FIG. 6 is not performed, and the display target bone numbers BIDU or the representative bone numbers BIDE are displayed at a fixed position outside the display target image Img1 toward the upper right thereof. In this case, a configuration may be adopted wherein a plurality of bone numbers are not displayed simultaneously. It is preferable for the bone number to be displayed in response to specifying operations within the display target image Img1 by the user. An example of such a configuration is that in which the bone number of a bone corresponding to the display target bone numbers BIDU or the representative bone numbers BIDE is displayed at the upper right of the display target image Img1 when the bone is clicked on. Next, the steps of the image display process, which is the embodiment of the present invention, will be described with reference to the flow chart of FIG. 3. The steps of the process are realized by control exerted by the control section 27 of the image processing work station 2. First, when the image display program of the present invention is started up at the image processing work station 2, the control section 27 calls on the bone number display setting receiving section 22. The bone number display setting screen is caused to be displayed on the display screen, and the bone number display setting receiving section 22 receives specification of display target bone numbers BIDU, the display method DM, and the display position DP (step 1). The display target bone numbers BIDU, the display method DM, and the display position DP specified by the user are stored in a predetermined memory region of the image processing workstation (step 1: YES). On the other hand, in the case that the user did not input any specifications, (step 1: NO), the bone number display setting receiving section 22 stores predefined default display target bone numbers BIDU, a predefined default display method DM, and a predefined default display position DP are stored in the predetermined memory region (step 2). Thereafter, the bone number display setting receiving section 22 transmits a “reception completed” message to the control section 27. When the “reception completed” message is received, the control section 27 calls on the original image/bone information obtaining section 21, and transmits the examination ID, the series ID and the like which are obtained from the startup parameters thereto. The original image/bone information obtaining section 21 transmits a search request to the image server 3 with the examination ID, the series ID, and the like as search keys. The image server 3 extracts three dimensional original image data Img0 and bone information BI (bone numbers BIDn and original bone position information COn) by searching the image database 4, and transmits the three dimensional original image data Img0 and the bone information BI to the original image/bone information obtaining section 21. The original image/bone information obtaining section 21 receives the three dimensional image data Img0 and the bone information BI from the image server 3, stores them in a predetermined region of the hard disk of the image processing work station 2, and transmits a “three dimensional data Img0 obtainment completed” message to the control section 27 (step 3). When the “three dimensional data Img0 obtainment completed” message is received, the control section 27 calls on the display target image obtaining section 23, and transmits the slice number m0 of the display target axial tomographic image, which is included in the startup parameters, and the storage location of the three dimensional original image data Img0 thereto. The display target image obtaining section 23 obtains image data that represents an axial tomographic image corresponding to the slice number m0 from the three dimensional original image data Img0 as a display target image Img1. The display target image obtaining section 23 stores the display target image Img1 and correspondence information R0, 1 in a predetermined memory region, and transmits a “display target image obtainment completed” message to the control section 27 (step 4). Note that in the present embodiment, the slice number m0 is stored in the predetermined memory region as the correspondence information R0, 1. When the “display target image obtainment completed” message is received, the control section 27 calls on the bone position specifying section 24, and transmits bone number information BIDn, original bone position information COn for each bone, the correspondence information R0, 1, and the display target bone numbers BIDU thereto. The bone position specifying section 24 specifies the positions of bones identified by the display target bone numbers BIDU within the display target image Img1, based on the transmitted information. The bone position specifying section 24 then stores display bone position information CDU in a predetermined memory region, and transmits a “bone position specifying process completed” message to the control section 27 (step 5). When the “bone position specifying process completed” message is received, the control section 27 judges whether “Display Representative Bone Number Only” has been selected as the display method DM at step 1 (step 6). In the case that the judgment at step 6 is affirmative (step 6: YES), the control section 27 calls on the representative bone number determining section 25, and transmits the display target image data Img1, the display target bone numbers BIDU, and the display bone position information CDU thereto. The representative bone number determining section 25 determines the representative bone number BIDE to be displayed along with the display target image Img0 from among the display target bone numbers BIDu, based on the information transmitted thereto. The representative bone number determining section 25 stores the representative bone number BIDE and display bone position information CDE for the bone identified by the representative bone number BIDE in a predetermined memory region, and transmits a “representative bone number determination completed” message to the control section 27 (step 7). When the “representative bone number determination completed” message is received, the control section 27 proceeds to the next step. On the other hand, if “Display All” is selected as the display method DM (step 6: NO), step 7 is skipped. Next, the control section 27 calls on the display control section 26, and transmits the representative bone number BIDE and the display bone position information CDE of the bone identified by the representative bone number BIDE along with the display target image data Img1 and the display position information DP thereto in the case that they are stored in the memory. Otherwise, the control section 27 transmits the display target bone numbers BIDU and the display bone position information CDU of the bones identified by the display target bone numbers BIDU along with the display target image data Img1 and the display position information DP to the display control section 26. The display control section 26 causes the display target image Img1 to be displayed on the display screen, and also displays the transmitted bone number (BIDE or BIDU) according to the display position information DP (step 8). In the case that “Display All” is selected as the display method DM for the display target bone numbers BIDU, the display target bone numbers BIDU of bones are displayed along with the display target image Img1, if they are present within the display target image Img1. On the other hand, in the case that “Display Representative Bone Number Only” is selected as the display method DM for the display target bone numbers BIDU, only the representative bone numbers BIDE, which are determined from among the bones identified by the selected display target bone numbers BIDU and are present within the display target image Img1, are displayed along with the display target image Img1. Here, the user may perform an operation to switch the image which is being displayed on the display screen. For example, the user may select a display target image Img1 by a clicking operation using a mouse, then switch the display to an axial tomographic image having a slice number m0+1, by operating the scrolling wheel of the mouse. Alternatively, the user may cause an operation menu to be displayed by operating a mouse or the like, then select a desired type of image (an axial image having a slice number m0+1, for example) from the displayed menu, to switch the display from the display target image Img1 to a different image. If the control section 27 detects such a switching operation (step 9: Switch Displayed Image), information that specifies the next image to be displayed (slice number m0+1 in the example described above) is obtained. The obtained information is transmitted to the display target image obtaining section 23, and the display target image obtaining section 23 is caused to obtain correspondence information R0, 2 (slice number m0+1 in the example described above) from the three dimensional original image (step 4). Bone number information BIDn, original bone position information COn for each bone, the correspondence information R0, 2, and the display target bone numbers BIDU are transmitted to the bone position specifying means 24. The bone position specifying means 24 is caused to specify display bone position information CDU (step 5). In the case that the “Display Representative Bone Number Only” is selected as the display method DM (step 6: YES), the representative bone number determining section 25 receives the display target image data Img2, the display target bone numbers BIDU, and the display bone position information CDU. The representative bone number determining section 25 is caused to determine the representative bone number BIDE to be displayed along with the display target image Img2 from among the display target bone numbers BIDu (step 7). Then, the display target image Img2, the bone numbers (BIDE or BIDU), the display bone position information (CDU or CDE), and the display position information DP are transmitted to the display control section 26, and the display target image Img2 is caused to be displayed on the display screen, along with the bone numbers (BIDE or BIDU), according to the display position information DP (step 8). Bone numbers corresponding to the next display target image Img2 are displayed in this manner. In the case that the user performs another operation to switch the image which is to be displayed on the display screen, the control section 27 detects the operation (step 9: Switch Displayed Image) the processes of step 4 through step 8 are repeated, and a next image is displayed along with the bone numbers (BIDE or BIDU), according to display position information DP. On the other hand, in the case that the user performs an operation to complete display of images, the control section 27 detects the operation (step 9: Complete Display), and the process ends. As described above, in the present embodiment, when the display control section 26 causes the display target image Img1 to be displayed on the display screen, the bone number display setting section 22 receives selection regarding the display target bone numbers BIDU to be displayed along with the display target image Img1. The bone position specifying section 24 specifies the positions CDU of the bones, which are identified by the display target bone numbers BIDU, within the display target image Img1, based on the bone information BI, in which the bone numbers BIDU of vertebral bones and ribs and original bone position information COn thereof within the three dimensional original image Img0 are correlated, and the correspondence information R0, 1 that represents the correspondence of positions between the three dimensional original image Img0 and the display target image Img1. The display target bone numbers BIDU are displayed along with the display target image Img1 such that a user can visually recognize that the bones which are identified by the display target bone numbers BIDU are displayed within the display target image Img1 at the specified positions CDU. Accordingly, only bone numbers BIDU which are desired by the user are displayed along with the display target image Img1, from among the plurality of bone numbers corresponding to the bones within the display target image Img1. Therefore, deterioration in visibility of the display target image Img1 due to the bone numbers being overlapped thereon and displayed can be reduced, while maintaining the ease with which the positions of the bones identified by the selected bone numbers BIDU are understood. In addition, the user interface, an example of which was illustrated FIG. 4 as the bone number display setting screen, is employed to select the display target bone numbers BIDU. The user interface enables selection of display target bone numbers in groups of “vertebral bones” and “ribs”, which include pluralities of bone numbers. Therefore, it is possible to select the bone numbers of all of the vertebral bones and all of the ribs as a bundle to be the display target bone numbers BIDU. Thereby, operations are simplified and operability is improved. Meanwhile, individual bone numbers are also enabled to be selected from the list box. Therefore, the display target bone numbers BIDU can be finely set, according to the purposes of image diagnosis, user preference, and the like. Further, the example of the user interface illustrated in FIG. 4 enables selection of “Display Representative Bone Number Only” as the display method DM. In the case that this option is selected, the representative bone number determining section 25 automatically determines representative bone numbers BIDE which are effective for image diagnosis, from among the plurality of display target bone numbers BIDU, based on the predetermined rule that employs the type of the display target image Img1, the type of the display target bone numbers BIDU, and the properties of the distribution of positions of bones which are
{'bibliographic_information': "{'country': 'US', 'doc-number': '12385737', 'kind': 'B2', 'date': '20090417', 'extension': '906', 'invention_title': 'Image display apparatus, image display control method, and computer readable medium having an image display control program recorded therein'}", 'source_file': './grant/2013/ipg130226.xml', 'source_data': 'USPTO-Grant'}