Abstract:
A picture archiving communication system for medical application includes least one work station, a data base, including a low-speed recording medium and a high-speed recording medium, for storing image data collected by a diagnosing apparatus unit. When a transfer command for desired image data is sent from the work station to the data base, the image data from the image data registered in the data base is read-out to the work station. A migration processing unit copies image data stored in the low-speed recording medium to the high-speed recording medium in the data base. A file management unit is provided, including a management table for storing a migration index number corresponding to at least one image data in the high-speed recording medium, which was subjected to the migration processing, and including a record indicating whether the image data stored in the high-speed recording medium was accessed after the migration processing. This system may further determine whether the image data stored in the high-speed recording medium from the management table has been accessed, and, if the image data has been accessed, deleting the image data from the high-speed recording medium from the earliest accessed one.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a picture archiving communication system for medical application (hereinafter referred to as &#34;PACS&#34;) having a data base for archiving medical images and accompanying data. 
     2. Description of the Related Art 
     A standard PACS has a structure as shown in FIG. 1. As shown in FIG. 1, diagnosing apparatuses 100 include a CR (Computed Radiography), an X-CT (x-ray tomographic imaging apparatus), an MRI (nuclear magnetic resonance imaging apparatus), a DF (digital fluorography apparatus), a US (ultrasonic diagnosing apparatus) and an NM (nuclear medicine apparatus). Image data collected by the various diagnosing apparatuses 100 is registered in a data base 300 via a network 200. On the other hand, when image data is referred to by work stations 400 (WS) arranged at various locations, a desired image index (ID) (e.g. a number assigned to each image) or an examination index is delivered from the work station 400 to the data base 300 to request transfer of image data. In response to a command from a system manager 500, image data corresponding to the work station 400 (WS) is transferred and displayed on an image display such as a CRT. 
     The data base 300 of the PACS, as shown in FIG. 2, comprises a optical disc library 310 having an optical disc drive 312, a magnetic disc drive 320, a system control unit 350, and a network interface 340. These devices are connected to a data bus 330. In this case, the system control 350 comprises a CPU 352 including a memory, an optical disc file management unit 354, and a magnetic disc file management unit 356. 
     In the data base system having the above structure, image data is normally stored in an optical disc drive 312. If the optical disc library 310 including a plurality of optical disc drives 312 is used, a large quantity of image data can be stored. In this case, however, the access time increases to several-ten seconds. If image data is stored in the magnetic disc drive 320, the access time of image data can be decreased. However, the storage capacity of the magnetic disc drive 320 is lower than the optical disc drive 312. 
     In general, among image data stored in the optical disc drive 312, image data likely to be accessed in the future (within a few days) is estimated, and such data is copied from the optical disc 312 to the magnetic disc drive 320 in advance. This processing is called &#34;migration processing&#34;. 
     FIG. 3 is a view for explaining the overall operation of the PACS in the &#34;migration processing&#34; mode. Referring to FIG. 3, the system manager 500 supplies at least one image index (&#34;image ID&#34; hereinafter) to the data base 300. The image ID is supplied to the CPU 352 of the system control unit 350 in the database 300 shown in FIG. 2. Then, the system control unit 350 accesses the optical disc file management unit 354 and finds the physical address for the optical disc drive 312, thereby reading out the corresponding image data. Subsequently, the system control unit 350 accesses the magnetic disc file management unit 356 and finds the address to be written, thereby writing image data read out from the optical disc drive 312 at the corresponding address of the magnetic disc drive 320. 
     FIG. 4 is a flow chart showing the migration processing in detail. 
     When a program is activated by a migration command from the system manager 500, each image ID is read out one by one from the memory provided within the CPU 352 (step ST1). 
     Then, the optical disc file management unit 354 is accessed, and the physical address associated with the image ID of the optical disc drive 312 is found (step ST2). In step ST3, it is determined whether the image data corresponding to the image ID is present at the address of the optical disc drive 312. If &#34;NO&#34; in step ST3, the arm of the optical disc library 310 is actuated, and a desired optical disc drive 312 is mounted (step ST4). If &#34;YES&#34; in step ST3, or after step ST4, desired image data is read out from the optical disc drive 312 (step ST5) and the control routine goes to step ST6. In step ST6, the magnetic disc file management unit 356 is accessed, and the address for write of desired image data is found. The image data corresponding to the image ID is written at the corresponding address of the magnetic disc drive 320 (step ST7). 
     Referring to the flow chart of FIG. 4, the processing of one image ID was described. After the steps ST1 to ST7 are completed, the control routine goes back to step ST1, and the same processing is repeated. Once the migration processing for all desired image IDs have been completed, the completion is told to the system manager 500 (step ST8) and the entire processing is finished. 
     After the end notice of the migration processing is transmitted to the system manager 500, the system manager 500 supplies a command to the work station 400, as shown in FIG. 3, to read out all image IDs which have been subjected to the migration processing. Thereafter, a command for reading the image ID is supplied from the work station 400 to the data base 300. Thus, desired image data is transferred from the magnetic disc drive 320 to the work station 400. 
     In the PACS with the above data base 300, the capacity of the magnetic disc drive 320 is limited. Thus, it is necessary to delete unnecessary files on an as-needed basis. In this case, the magnetic disc drive 320 stores, in a mixed manner, modalities, data registered by the work station, etc., data read out from the optical disc drive 312 in the migration processing, data used temporarily as buffer, and data for backup of data on the system disc and memory, etc. Accordingly, when data in the magnetic disc drive 320 is deleted, such data is generally deleted by referring to the earliest date of access of files. 
     However, when data transfer is performed in the data base 300 after a certain period from the migration processing, it is possible that part of a desired file is deleted before the data transfer. The fact of deletion of data is not detected in the system manager 500 or work station 400. Consequently, when data is accessed by the work station 400, desired image data is not in the magnetic disc drive 320 and the optical disc drive 312 must be accessed once again. Thus, the wait time increases considerably. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a picture archiving communication system for medical application (PACS) capable of effectively performing migration processing and increasing the access speed of image data. 
     According to one aspect of the invention, there is provided a picture archiving communication system for medical application, comprising: 
     at least one work station; 
     a data base, including a low-speed recording medium and a high-speed recording medium, for storing image data collected by a diagnosing apparatus; 
     means for reading out, when a transfer command for desired image data is sent from the work station to the data base, the image data from the image data registered in the data base and transfers the read-out image data to the work station; 
     migration processing means for performing migration processing in which image data stored in the low-speed recording medium is copied to the high-speed recording medium in the data base; and 
     file management means including a management table for storing a migration index number corresponding to at least one image data in the high-speed recording medium, which was subjected to the migration processing, and a record indicating whether the image data stored in the high-speed recording medium was accessed after the migration processing. 
     This system may further comprise data deleting means for determining whether the image data stored in the high-speed recording medium from the management table has been accessed, and, if the image data has been accessed, deleting the image data from the high-speed recording medium from the earliest accessed image data. 
     According to the PACS of this invention, the migrated image data on the high-speed recording medium can preferentially be stored on the management table of the file management means of the data base. Thus, the user can always access data within a predetermined period. Further, since image indexes can collectively be managed for each migration index, the control of the entire system is easy. 
     In addition, the image data can be deleted from the earliest accessed image file, by referring to the access record (e.g. flag) indicating whether the image data was accessed as header information of the data in the high-speed recording medium. Thus, non-accessed data is not deleted from the high-speed recording medium. 
     As has been stated above, the present invention can provide a picture archiving communication system for medical application (PACS) capable of effectively performing migration processing and increasing the access speed of image data. 
     Additional objects and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention. The objects and advantages of the present invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the present invention and, together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the present invention in which: 
     FIG. 1 is the overall structure of a conventional picture archiving communication system for medical application (PACS); 
     FIG. 2 shows the structure of a conventional data system; 
     FIG. 3 illustrates the operation of the conventional system in response to commands and requests; 
     FIG. 4 is a flow chart illustrating the migration processing in the conventional data base; 
     FIG. 5 shows the structure of a data base system of a PACS according to an embodiment of the invention; 
     FIG. 6 shows a migration management table according the embodiment; 
     FIG. 7 shows an address management table according the embodiment; 
     FIG. 8 is a flow chart illustrating the migration processing in the data base according to the embodiment; 
     FIG. 9 is a flow chart illustrating the procedure for data deletion according to the embodiment and 
     FIG. 10 illustrates the operation of the entire system in response to commands and requests according the embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of the present invention will now be described with reference to the accompanying drawings. 
     FIG. 5 shows the structure of a data base system, according to the present invention, for use in the PACS shown in FIG. 1. In FIG. 5, the same parts as in FIG. 2 are denoted by like reference numerals, and a description thereof is omitted. Only the differences are described. The overall structure of the PACS shown in FIG. 1 is unchanged. 
     In this embodiment, as shown in FIG. 5, the magnetic disc file management unit 356 is provided with a migration management table 356A and an address management table 356B. A migration index issue unit (migration ID issue unit) 358 is newly provided and connected to the data bus 330. 
     A unique number in the system may be used as a migration ID number issued by the migration ID issue unit 358. For example, when a migration ID number is issued by the data base system, the migration ID number may be a combination of a data base number assigned to the data base 300 and a sequential number corresponding to the order of issued ID numbers in the data base 300. 
     FIG. 6 shows an example of the migration management table 356A. Image IDs transferred by migration are linked by using migration IDs as keys. Since a migration ID number is linked to the next migration ID number, only the migration ID number can be searched until a desired migration ID number is found. For example, a search can be conducted in a route from migration ID number 001 to migration ID number 002, or in a route from migration ID number 001 to migration ID number 002 via image ID #5 and image ID #7. 
     FIG. 7 shows an example of the address management table 356B. The table 356B can record a storage address in the magnetic disc drive 320 for each image, a storage address in the optical disc drive 312 for each image, a migration ID number for each image, and the occurrence of access (access record) for each image. Since the contents of this table are fixed-length data, this table can be realized by using a fixed-length file. 
     For example, in FIG. 7, the image of image ID #2 is stored at address 7FCD of the magnetic disc drive 320 and at address 1025 of the optical disc drive 312, and it is migrated at migration ID number 4. The access record is &#34;NULL&#34;, which means that an access or transfer of data to the work station 400 has been performed. 
     In FIG. 7, the image of image ID #5 is migrated at two migration ID numbers 4 and 1. The access record is &#34;1&#34;, which means that the image of image ID #5 has been accessed or transferred to migration ID number 1, but it has not been accessed to migration ID number 4. That is, transfer to the work station 400 is not finished. Thus, image ID #5 cannot be deleted. In addition, in FIG. 7, the image of image ID #1048 has been migrated by migration ID number 7 and accessed by migration ID number 7. Accordingly, the image of image ID #1048 is normally at top priority for deletion. 
     The operation of the PACS with the above structure will now be described. 
     When at least one image ID is sent to the data base 300 from the system manager 500, the CPU 352 of the system control 350 is activated and the migration processing, as shown in the flow chart of FIG. 8 is performed. 
     Referring to FIG. 8, when the migration processing is started, the migration ID number is issued from the migration ID issue unit 358 and the image ID is stored in the memory of the CPU 352 (step ST10). Image IDs stored in the memory of the CPU 352 are read out one by one (step ST11), and it is determined whether all desired image IDs have been read out (step ST12). 
     If &#34;NO&#34; in step ST12, the address management table 356B shown in FIG. 7 is referred, and a medium storing the image in question is checked (step ST13). Subsequently, it is determined whether the image is stored in the magnetic disc drive 320. If the image is in the magnetic disc drive 320, the control routine goes back to step ST11. If the image is not in the magnetic disc drive 320, the control routine goes to step ST15 (step ST14). 
     In step ST15, the optical disc file management unit 354 is accessed, and the physical address of the optical disc drive 312 is obtained. Image data corresponding to the optical disc drive 312 is read out, and the read-out image data is copied to the magnetic disc drive 320 (step ST16). In step ST17, the magnetic disc drive address corresponding to the image ID in the address management table 356B shown in FIG. 7 is rewritten from &#34;NULL&#34; to the address of the destination magnetic disc drive. The control routine returns to step ST11 and the next image ID is read out, thus performing the same processing as was described above. 
     If &#34;YES&#34; in step ST12, the migration ID and the end of read are told to the system manager 500 (step ST18). Then, the whole migration processing is completed. 
     The processing for deleting image data stored in the magnetic disc drive 320 will now be described with reference to the flow chart shown in FIG. 9. 
     When a program for deleting image data stored in the magnetic disc drive 320 is started, the header (address) of the image file stored in the magnetic disc is read out by referring to the address management table 356B (step ST21). 
     Whether the read-out image file has been migrated is determined on the basis of the migration ID number of the address management table 356B (step ST22). If &#34;YES&#34; in step ST22, it is determined whether the read-out image file has been accessed from the work station 400 on the basis of the access record in the address management table 356B (step ST23). If &#34;NO&#34; in step ST23, the control routine returns to step ST21. If &#34;YES&#34; in step ST23, the latest access date and time are recorded in the magnetic disc file management unit 356 (step ST24). If &#34;NO&#34; in step ST22, the control routine goes to step ST24 and the latest access date and time are recorded in the magnetic disc file management unit 356. 
     Once the latest access date and time have been recorded in the magnetic disc file management unit 356 in step ST24, it is determined whether the latest access date and time relating to all image data stored in the magnetic disc drive 320 have been recorded (step ST25). If &#34;NO&#34; in step ST25, the control routine returns to step ST21 and the header of the next image file is read out. If &#34;YES&#34; in step ST25, the files (image IDs) are successively deleted from the earliest accessed one (step ST26). 
     FIG. 10 is a view illustrating the entire operation of the PACS in the &#34;migration processing&#34; mode in the present invention. 
     When a migration command (image ID) is output from the system manager 500 to the data base 300, the data base 300 executes the above-described migration processing. Once the migration processing is completed, an end notice is sent to the system manager 500 (i.e. notice of migration ID number). A read command (migration ID number) is transmitted from the system manager 500 to the work station 400. Thereafter, a read request (migration ID number) is output from the work station 400 to the data base 300. Thus, image data accessed by the migration ID number is transferred from the data base 300 to the work station 400. 
     As has been described above, according to the apparatus of this embodiment, the magnetic disc file management unit 356 is provided with the migration management table 356A and address management table 356B. Thereby, the files in the magnetic disc drive 320 are managed. 
     Specifically, when the migration command is output from the system manager 500, the migration management table 356A records, in a linked manner, the ID number (migration ID number) unique to the system indicating the class of migration, which is issued from the migration ID issue unit 358 provided in the data base 300, and at least one image ID managed collectively by this migration ID number as header information of the image data stored in the magnetic disc drive 320. The address management table 356B comprises the image ID of image data written in the magnetic disc drive 320, physical address of the magnetic disc drive 320, physical address in the optical disc drive 312, migration ID number, and access record showing an access number (e.g. a flag) indicating the occurrence of access in the work station 400. 
     As has been described above, according to this invention, the migrated image data on the magnetic disc drive 320 is preferentially accessed by the management tables 356A and 356B of the magnetic disc file management unit 356 of the data base 300. Thus, data access can always be performed within a predetermined period. Since image IDs can be collectively managed by each migration ID number, the control of the overall system is easy. In addition, since the image data can be deleted from the earliest accessed file, by referring to the access record indicating the occurrence of access as header information of image data in the magnetic disc drive 320, it is possible to prevent non-accessed data from being erroneously deleted from the magnetic disc drive 320. The wait time until the transfer of desired image data can remarkably be reduced. 
     In the above embodiment, the data base 300 is provided with the migration ID issue unit 358 and the migration ID number is issued in response to the migration command from the system manager 500. However, it is possible that the system manager 500 issues the migration ID number beforehand and the migration ID number is delivered to the data base 300. 
     In the above embodiment, a single data base 300 is managed by migration IDs. However, it is possible to manage image data stored separately in two or more data bases 300 by a single migration ID. 
     In the above embodiment, the flag is written in the access record when the occurrence of access is recorded in the access record. However, if it is determined whether image data can be deleted, any recording method, other than use of the flag, is available. For example, in FIG. 7, image ID #5 is migrated by migration ID numbers 1 and 4 and the access record indicates the access of migration ID number 1. When the migration ID number 1 is accessed, it is possible to delete migration ID number 1 and retain migration ID number 4, while leaving the access record of &#34;NULL&#34;. In this case, it is understood that the migration ID number 4 has not been accessed. Accordingly, the image data of the image ID, the migration ID number of which is &#34;NULL&#34;, is an image to be deleted. In this case, the access record is not needed. 
     The above embodiment is directed to the case where migration management and address management of the image ID are performed. However, a check ID may be substituted for the image ID. 
     In the above embodiment, image IDs stored in the memory of the CPU are read out one by one. A plurality of image IDs may be read out all in one. 
     Additionally, in the above embodiment, the corresponding image IDs are migrated one by one. However, the migration may be performed per one diagnosis. 
     various changes and modifications may be made to the present invention without departing from the spirit of the invention. 
     Additional advantages and modifications will readily occur to those skilled in the art. Therefore the present invention in its broader aspects is not limited to the specific details, representative devices, and illustrated examples shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.