Abstract:
A PACS including a source of medical data, such as a CT unit ( 20 ), a workstation ( 100 ) capable of creating an image of the data, and a local area network ( 40 ). A server ( 60 ) stores compressed medical data in a RAID ( 70 ) and also in a magneto-optical unit ( 80 ) and a tape DLT unit ( 90 ). The tape unit ( 90 ) has a transfer rate equal to or greater than the transfer rate of the RAID.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to picture archive and communication systems (PACS), and more specifically relates to archiving data in such systems. 
     Archive storage in PACS systems is provided for backing up images and other data once the data is not necessary at a short-term storage site. The archives are not redundant and there is a possibility that large quantities of information may be lost in the event of failure or servicing of the archive. This invention addresses the problem and provides one solution. 
     BRIEF SUMMARY OF THE INVENTION 
     The preferred embodiment of the invention is useful in a picture archive and communication system for archiving medical data. In such an environment, the preferred embodiment typically includes a source of medical data, a network, a first memory and a second memory. Data is received from the source of medical data, preferably over the network, and is stored, preferably in the first memory. The data then is transferred from the first memory to the second memory, preferably via the network, before the capacity of the first memory is exceeded. At some time, the stored data is transferred from the first memory or the second memory to the workstation to create an image. 
     By using the foregoing techniques, security can be provided for image data and other medical data. The data can be quickly and conveniently restored in the event of a failure, during servicing and during archive or medium replacement. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic block diagram of a preferred form of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG. 1, a preferred form of the invention includes a radiology information system (RISIHIS)  10  which provides image data derived from x-rays of patients. A computed tomography (CT) unit  20  provides image data derived from scans of patients, and a magnetic resonance (MR) unit  30  provides image data from additional scans of patients. System  10  and units  20  and  30  also may provide text data about the image data generated by the respective units or about the circumstances of the patients or procedures from which the image data was derived. For example, the system and units may provide the name of the patient, the date of the creation of the image data, and various control numbers assigned to the procedures or image data. 
     The image data and text data are transmitted over a conventional local area network  40  to a modality interface unit (MIU)  50  in a well known manner. One example of MIU  50  is model number 2223612 made by General Electric Company. 
     Unit  50  compresses the image data in a well known manner and provides the compressed data, as well as the text data, to an information management server (IMS)  60  via network  40 . One example of IMS  60  is model number 2244014 made by General Electric Company. The text data is stored in a data base in IMS  60 . The compressed image data is transferred by IMS  60  to a short-term memory image storage unit (ISU)  70  which may comprise a RAID unit. RAID units are well known in PACS and need not be described in detail. Although ISU  70  is able to rapidly store data and access such data, its storage capacity is limited. As a result, data stored in ISU  70  frequently is read from ISU  70  by IMS  60  and is transferred via network  40  to a magneto-optical disk (MOD) memory unit  80 . MOD  80  may be arranged as a jukebox managing, for example, 500 disks, each with a capacity of at least 5 gigabytes. Data may be written to and read from MOD memory  80  at a rate of at least 4 megabytes per second, and preferably 5 megabytes per second. One example of MOD  80  is model M-500 made by Plasmon. 
     In order to provide improved archiving of compressed image data, a digital logic tape (DLT) memory unit  90  is connected to network  40  as shown. DLT  90  provides a tape drive which moves a tape medium on which compressed image data is stored. DLT  90  has a storage capacity of at least 20 gigabytes and preferably 40 gigabytes. Data is written to and read from DLT  90  at a rate of at least 6 megabytes per second and preferably 10 megabytes per second. Examples of DLT  90  include model DLT 7000 made by Quantum and model 9840 made by StorageTek. 
     During use, at frequent intervals, IMS  60  reads data from ISU  70  and writes the data to DLT  90  via network  40 . As a result, DLT  90  has a data transfer rate at least equal to the data transfer rate of ISU  70 . The ability of DLT  90  to write data read directly from ISU  70  at the same rate as data is written to ISU  90  is an advantage because it reduces the risk that some data will be lost. The applicants have found that employing a tape unit, such as DLT  90 , for this purpose also has cost advantages. Tape units are generally less expensive than RAIDs or magneto-optical units of the same capacity. By providing a tape unit with a data transfer rate as great as the data transfer rate of the ISU enables data to be archived with a degree of safety and economy not previously obtainable. Another advantage of the described system is the use a single server, IMS  60 , to handle data transfers among ISU  70 , MOD  80  and DLT  90 . This arrangement enables a single operating system to be employed which improves software efficiency and reduces costs. 
     The preferred embodiment also includes conventional medical workstations  100  which create a viewable image on a monitor in response to image data received from any of ISU  70 , MOD  80  or DLT  90 . In response to a request by a user, IMS  60  accesses the desired data on one of ISU  70 , MOD  80  or DLT  90 , decompresses the data, and transfers the decompressed data via network  40  to a designated one of workstations  100 . 
     Those skilled in the art will recognize the preceding is merely a description of the preferred embodiments which may be altered and modified without departing from the true spirit and scope of the invention as defined in the accompanying claims.