JP2000222257A - Data storing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data storing device which minimizes the deterioration of the accessing performance and reliability of a storing means such as a magneto-optical disk library and makes it possible to apply a processor of a more inexpensive work station. SOLUTION: Original data is intermediately written in a data storing means 46 by an original data recording means 41. A data compressing means 42 prepares compressed data compressed by at least two different compressibility to write it in a data storing means 46. Original data is erased from the means 46 by a data erasing means 43 at the point of the time when at least compressing processing is finished. Compressed data is erased from the means 46 in the order of raising the compressibility according to a passing time after storing of data by a passing time measuring means 44 and a compressed data erasing means 45.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a data storage device for storing a plurality of data, and more particularly, to a data storage device capable of increasing a data compression rate in accordance with an elapsed time (access frequency) after data storage. It is about.

[0002]

2. Description of the Related Art FIG. 1 shows an example of a data management system using a data storage device of this type, here a medical image data management system in a hospital radiology department. Diagnostic imaging device (modality) for capturing medical image data and outputting it as medical image data, 2 is a data storage device for storing medical image data for several years, and 3 is image interpretation for creating a report while displaying medical image data on a CRT. Terminal.

FIG. 2 shows an example of a data storage device. In the figure, reference numeral 21 denotes a workstation for controlling and managing data read / write; 22, a magnetic disk RAID for reading / writing data at high speed; This is a magneto-optical disk library that can store data and can be accessed randomly.

[0004] In the radiology department, an X-ray photograph of a patient is taken at the request of another department in the hospital, the medical image data is interpreted (the symptoms of the patient are read from the image), and a report is created. Is returned to the requesting department. In this case, the medical image data output from the diagnostic imaging device (modality) 1 is first stored in the data storage device 2. The accumulated medical images are read by a radiologist in the afternoon or within a few days of the day. For this reason, the medical image data is read from the data storage device 2 to the image reading terminal 3. However, when comparison with the past medical image data is necessary, the past medical image data stored in the data storage device 2 is also read. Also read out together. When the reading is completed, a report is created,
The created report is stored in the data storage device 2 or another storage device in preparation for output to the department of the request source.

[0005] In the image reading terminal 3, the medical image data for which the image reading has been completed or the past medical image data read for comparison is deleted immediately and is not returned to the data storage device 2. As described above, the medical image data is stored in the data storage device immediately after being output from the modality, but in a large or medium-sized hospital having many modalities, the amount of generated medical image data per day is several GB, Since it reaches 1 TB annually, the required storage capacity of the data storage device is very large, several TB or more. For this reason, in order to reduce the required storage capacity inside the data storage device, medical image data is stored in a form with a different compression ratio according to the intended use.

FIG. 3 shows a flow of storing medical image data in a conventional medical image data management system. The storing (storing) is performed while changing the compression ratio in three steps according to the elapsed time after obtaining the medical image data. It shows how it is done.

First, the first step of storage is storage for the purpose of image interpretation, and medical image data output from the modality is immediately stored in the data storage device. In this case, since it is important that medical image data can be read and written at high speed, the medical image data is stored without compression on a magnetic disk RAID that can be accessed at high speed.

Next, when the image reading is completed, the medical image data is re-stored as medical image data for comparative image reading. This is the second step of accumulation. All of the medical image data accumulated in the first step is subject to interpretation, whereas only a part of the medical image data in the second step of accumulation is used for comparative interpretation. That is, it can be said that the medical image data for comparative reading has a low access frequency.

[0009] In addition, since past medical image data for comparative image reading can usually be searched from the stage when a patient visits a reception at a hospital, it is possible to read ahead using the time until the patient visits a radiology department. .

For this reason, in the second step, the medical image data is reversibly compressed and then stored in the magneto-optical disk library of the data storage device. In this case, the medical image data is read from the magnetic disk RAID after the image reading is completed, reversibly compressed, and re-stored in the magneto-optical disk library.
At this point, the original medical image data in the magnetic disk RAID stored for image reading is completely unnecessary and is deleted. The medical image data in the second step of accumulation is accumulated for a period during which there is a high possibility that the same patient will return to the hospital for a medical examination or the like, for example, for about one year.

When about one year has passed in such a state, the meaning of the medical image data as the past medical image data for comparison becomes weak. However, according to the medical law, 2
The medical law requires that medical image data be stored for three years under the Health Law. Furthermore, when special laws such as the pneumoconiosis law are applied, preservation for five years after photographing is required. The medical image data is then stored for several more years in accordance with legal preservation obligations.

In this case, the medical image data is recompressed to about 1/10 and stored in the magneto-optical disk library again as reference medical image data that can be interpreted to some extent. This is the third step of accumulation.

FIG. 4 shows a flow of recompression of medical image data in a data storage device of a conventional medical image data management system.

First, a disk medium on which reversibly compressed medical image data is recorded is stored in a magneto-optical disk library 23.
It is transported from the storage warehouse inside to the magneto-optical disk drive 24 (1).

Next, the medical image data is read by the magneto-optical disk drive 24, the medical image data is transferred to the workstation 21 (2), the compression is decompressed, and (3) the original data of the medical image data is reproduced. You. Further, the medical original image data obtained here is irreversibly compressed to 1/10 (4).

In the magneto-optical disk library 23, the disk medium in the magneto-optical disk drive 24 is returned to the storage warehouse (5), and a new disk medium for recording medical image data irreversibly compressed to 1/10 is stored. Is taken out of the storage warehouse and transported to the magneto-optical disk drive 24 (6).

Finally, the medical image data, which has been irreversibly compressed to 1/10, is transferred from the workstation 21 to the magneto-optical disk drive 24, and is recorded on the new disk medium (7). Is returned to the warehouse in the magneto-optical disk library 23 again (8).

[0018]

The magneto-optical disk library is a storage device that can be accessed randomly, and its reliability is guaranteed for decades. However, since the disk medium is transported by a robot hand, Generally, high access performance cannot be expected. The specific average access time is about 10 seconds.

Further, since it takes about several seconds to decompress medical image data of several tens MB, if a large or medium-sized hospital handles medical image data of several GB per day, Rewriting medical image data can take several hours. The above operation not only significantly deteriorates the access performance of the magneto-optical disk library, but also degrades the reliability of the robot hand.

Further, since it is necessary to decompress the medical image data which has been reversibly compressed, a workstation for performing these processes is required to have a larger work area and a higher calculation capability.

An object of the present invention is to minimize the deterioration of the access performance and reliability of storage means such as a magneto-optical disk library by omitting the data decompression work required when recompressing and recording such data. It is an object of the present invention to provide a data storage device capable of applying a processing device such as a workstation which is less expensive and less expensive.

[0022]

According to the present invention, in order to solve the above-mentioned problems, in a data storage device provided with data storage means for storing a plurality of data, original data recording means for directly writing original data to the data storage means And data compression means for reading the original data from the data storage means, creating compressed data obtained by compressing the original data at at least two different compression ratios, and writing the compressed data in the data storage means. Original data erasing means for erasing the original data from the data storage means after completion, elapsed time measuring means for measuring the elapsed time from the time when the original data was written to the data storage means, and measurement of the elapsed time by the elapsed time measuring means. The compressed data having the same original data is deleted from the data storage means in ascending order of the compression ratio according to the elapsed time. Characterized by comprising a compressed data erasing means.

According to the above configuration, compressed data is created in advance by compressing the original data with at least two different compression ratios, and the compressed data having a low compression ratio is generated in accordance with the elapsed time (access frequency) after data storage. In order to sequentially erase data, in order to increase the data compression rate in accordance with the elapsed time after data storage, as in the related art, take out a disk medium from a magneto-optical disk library or the like, read out the compressed data,
There is no need to decompress and recompress this at a workstation or the like and write it back to the disk medium and store it again.

Therefore, it is possible to minimize the deterioration of the access performance and reliability of the storage means such as the magneto-optical disk library, and to replace the data storage device having the required performance with a less expensive magneto-optical disk library. And workstations.

The magneto-optical disk library creates at least two data groups for one original data, which are usually compressed at all necessary compression ratios. Although a somewhat larger storage capacity is required, data with a lower compression ratio, that is, data with a larger data amount, usually has a shorter storage period, so that an increase in the storage capacity does not pose a problem.

According to the present invention, there is provided a dedicated recording area for collectively recording data having the same compression rate for data compressed at a plurality of compression rates, and the recording area is divided into a plurality of blocks. And data storage means for erasing recorded data in block units.

According to the above configuration, since the data having the same compression ratio is collectively recorded in the same recording area, and the recording area is divided into a plurality of blocks, the fragmentation used when the recording area is used in a worm-like state. In addition, the recording data can be collectively erased in block units, so that it is not necessary to search for a data file having the same shooting month, for example. In the case of a library or the like, if one block is configured for each disk medium, data can be easily erased by erasing the entire disk medium.

[0028]

FIG. 5 shows an example of an embodiment of a data storage device according to the present invention. Here, similarly to the conventional example, an example in which the present invention is applied to a medical image data management system in a hospital radiology department. Is shown. In the figure, 41 is an original data recording means, 42 is a data compression means, 43 is an original data erasing means, 44 is an elapsed time measuring means, 45 is a compressed data erasing means, and 46 is a data storage means.

The original data recording means 41 writes the original data inputted from the diagnostic photographing apparatus into the data storage means 46 as it is. The data compressing means 42 includes a data storing means 46
, And creates compressed data obtained by compressing the original data with at least two different compression ratios, here, two compression ratios of 可逆 lossless compression and 1/10 irreversible compression. Write.

At least after the data compression processing in the data compression means 42 is completed, the original data erasing means 43 outputs information indicating that the data compression processing has been completed and that the image interpretation work in the image interpretation terminal has been completed (for example, ,
After the notification of the report is obtained, the corresponding original data is erased from the data storage unit 46 (note that the original data is erased when a predetermined set time T1, for example, one week has elapsed after the completion of the data compression process). May be used.)

The elapsed time measuring means 44 measures the elapsed time from when the original data is written to the data storage means 46. The compressed data erasing unit 45 includes the elapsed time measuring unit 4.
4, compressed data having the same original data according to the elapsed time measured in ascending order of compression ratio, in this case, data that has been losslessly compressed after a predetermined set time T2 (for example, one year) has passed, After a lapse of T3 (for example, three years), the data that has been irreversibly compressed is deleted from the data storage means 46.

Each of these means is realized by a software program on the work station 21 shown in FIG. 2, for example. FIG. 6 is a flowchart showing a software configuration corresponding to the above embodiment.

Here, only the portion relating to recording / erasing of original data and creation / erasing of compressed data are shown, and portions relating to reading of data for image interpretation, reading of data for comparison, decompression, and the like are shown. Is omitted because it is the same as the conventional case.

The storage means 46 comprises, for example, the magnetic disk RAID 22 and the magneto-optical disk library 23 shown in FIG. 2, and stores a plurality of data.

FIG. 7 shows a flow of storing medical image data in the medical image data management system according to the present invention.

In this example, in the first step of accumulation, the original data of the medical image data output from the modality is immediately transferred to the storage means 46 via the original data recording means 41, for example, the magnetic disk RAID, as in the conventional case. Is recorded in the data compression means 42.
All of the / 2 lossless compressed image data and 1/10 irreversible compressed image data are created and stored in the storage means 46, for example, in a magneto-optical disk library.

Then, in the second step of storage, when the original data erasing means 43 confirms the end of the above-described compression processing and the end of the image reading operation in the image reading terminal, the original data in the magnetic disk RAID of the storage means 46 is confirmed. Delete image data.

Further, in the third step of accumulation, when the elapsed time measuring means 44 measures the elapse of the predetermined set time T2, the compressed data erasing means 45 performs the reversible compression from the magneto-optical disk library of the storage means 46. The image data is erased (after that, if the set time T3 elapses, the irreversible compressed image data is also erased similarly).

According to the present embodiment, it is not necessary to read medical reversible compressed image data for re-compression in a magneto-optical disk library or the like, and it is possible to perform compression for re-compressing medical reversible compressed image data in a workstation or the like.・ Thawing work is not required. Specifically, in the flow of recompression of medical image data in FIG. 4, (1), (2),
The processes of (3) and (5) become unnecessary. At this time, the remaining processes of (4), (6), (7) and (8) are 1/10
This is essentially an indispensable operation of writing the medically irreversibly compressed image data compressed to the optical disk library or the like.

As a result, the writing of medical image data to the data storage device includes (1) writing of an original image, (2) writing (compression) of a reversible compressed image, and (3) writing (compression) of a lossy compressed image. In addition to this, the compression time and decompression time of medical image data are almost the same as in the conventional case where reading (decompression) of a lossless compressed image is necessary, and the original image is transferred to the magnetic disk RAID. Assuming that writing takes almost no time, the time required for storing medical image data is reduced to about 2/3.

On the other hand, as is apparent from FIG. 7, in the present embodiment, as compared with the conventional method, the storage area for recording the lossless-compressed image and the lossy-compressed image in the first step of accumulation is In the second step of accumulation, a new recording area for recording the lossy compressed image is required.

Here, the capacity of the medical original image data is M, the period of the first step of accumulation is T1, the period of the second step of accumulation is T2, the period of the third step of accumulation is T3, and the second step of accumulation is Assuming that the compression ratio of the medical image data in the first method is α2 and the compression ratio of the medical image data in the third step of accumulation is α3, the required storage capacity DO of the data storage device in the conventional method and the data storage device in the present embodiment The required storage capacity DN is: DO = (M × 1 × T1) + (M × α2 × T2) + (M ×
α3 × T3) DN = (M × (1 + a2 + α3) × T1) + (M × (α
2 + α3) × T2) + (M × α3 × T3).

Therefore, the increase rate β of the required storage capacity of the magneto-optical disk library is as follows: β = DN / DO−1 = ((1 + α2 + α3) × T1 +
(Α2 + α3) × T2 + α3 × T3) / (T1 + α2 ×
T2 + α3 × T3) −1 = ((a2 + α3) × T1 + α
3 × T2) / (T1 + α2 × T2 + α3 × T3)

Specifically, assuming that the first step of accumulation is up to one week, the second step is up to one year, and the third step is up to three years, T1 = 7 days, T2 = (365-7) days,
If T3 = (1095-365) days, and the image compression ratios in each step are α2 = 0.5 and α3 = 0.1,
The increase rate β of the required storage capacity is 0.154 (15.4%)
Becomes

In the third step, the compression ratio α3 = 0.
If it is set to 05, β = 0.098 (9.8%).

In the case of the present embodiment, the storage capacity of the data storage device is designed based on the prediction of the change in the number of patients over at least three years. It can be said that the fluctuation within.

FIG. 8 shows another example of the embodiment of the data storage device of the present invention, here another example of the data recording method in the data storage means.

That is, in the drawing, reference numerals 51, 52, and 53 denote dedicated recording areas in the data storage means, which are divided corresponding to original medical image data, reversible medical image data, and lossy medical image data. In addition, each of the recording areas 51, 52, and 53 is used by being divided into L, M, and N blocks. Each block is used in the order of the block number, and medical image data is sequentially written. (In general, the recording area 51 is formed on the magnetic disk RAID, and the recording areas 52 and 53 are formed on the magneto-optical disk library. Is done.)

Here, taking medical original image data as an example, at the same time as medical image data is generated by imaging,
The currently written No. The medical image data is sequentially written into the L blocks.

The data storage device checks the utilization of this block when the writing of each medical image data is completed or when the writing of the medical image data for one day is completed, and the utilization is determined in advance. When the value exceeds a certain value, the No. to which the next medical image data is to be written 1
Block is erased without checking the contents of the block. After that, no. The writing of the medical image data to the L block is continued, and ends when the writing of the medical image data to the NoL block becomes impossible.

Thereafter, the block in which the medical image data is to be written is stored in the already erased No. block. 1, and sequentially writes the medical image data again.

As described above, by dividing the recording area into blocks and erasing the recording area in block units,
The problem of fragmentation used when the recording area is wormy can be solved. In addition, since data is collectively erased in block units, for example, there is no need to search for medical image data with the same imaging month, and physical erasing is possible. If the blocks are configured, medical image data can be easily erased by erasing the entire surface of the disk medium. As a result, the access performance of the data storage device can be equivalently improved.

When storage devices having different access performances are mixedly used, the required access performance is high in the order of medical original image data, medical lossless compressed image data, and medical lossy compressed image data. It goes without saying that storage devices having high access performance should be allocated and used in the order of the compression ratio.

Although the embodiment has been described with reference to the case where medical image data is recorded in the data storage device, the present invention is not limited to the recording of medical image data, but is applicable to the storage of all types of data. it can.

[0055]

As described above, according to the present invention, in order to increase the data compression ratio in accordance with the elapsed time after data storage, a disk medium is taken out of a magneto-optical disk library or the like and compressed as in the prior art. Read data,
Since it is not necessary to decompress and recompress this in a workstation or the like and write it back to the disk medium and store it again, it is possible to minimize the deterioration in the access performance and reliability of the storage means such as the magneto-optical disk library. With
The data storage device having the required performance can be constituted by a less expensive magneto-optical disk library or workstation.

According to the present invention, data having the same compression ratio is recorded collectively in the same recording area, and the recording area is divided into a plurality of blocks. In addition to solving the problem of fragmentation, the process of searching for data to be erased is unnecessary and can be physically erased, so that the access performance of the data storage device can be further improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a medical image data management system in a hospital radiology department.

FIG. 2 illustrates an example of a data storage device.

FIG. 3 is a diagram showing a flow of storage of medical image data in a conventional medical image data management system.

FIG. 4 is a diagram showing a flow of recompression of medical image data in a data storage device of a conventional medical image data management system.

FIG. 5 is a functional block diagram showing an example of an embodiment of a data storage device of the present invention.

FIG. 6 is a flowchart showing a software configuration corresponding to an example of the embodiment of the data storage device of the present invention;

FIG. 7 is a diagram showing a flow of storage of medical image data in a medical image data management system using the data storage device of the present invention.

FIG. 8 is a diagram showing a data recording method showing another example of the embodiment of the data storage device of the present invention.

[Explanation of symbols]

1: diagnostic imaging device, 2: data storage device, 3: image reading terminal, 21: workstation, 22: magnetic disk R
AID, 23: magneto-optical disk library, 24: magneto-optical disk drive, 41: original data recording means, 42:
Data compression means, 43: original data erasing means, 44: elapsed time measuring means, 45: compressed data erasing means, 46: data storage means.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuaki Tanaka 3-19-2 Nishi Shinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Tomohiko Arikawa 3- 192-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo No. Nippon Telegraph and Telephone Corporation (72) Inventor Atsushi Sato 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Kazuhiro Morita 3- 192-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo No. Nippon Telegraph and Telephone Corporation (72) Hiroko Koyama Inventor 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Hiroaki Tanaka 3-19, Nishi-Shinjuku, Shinjuku-ku, Tokyo No. 2 Nippon Telegraph and Telephone Corporation F term (reference) 5B082 AA13 CA14 DE04 GA01

Claims (2)

[Claims] 1. A data storage device having data storage means for storing a plurality of data, comprising: an original data recording means for writing original data to the data storage means as it is; an original data read from the data storage means; Data compression means for creating compressed data compressed at at least two different compression ratios and writing the compressed data in a data storage means; and original data for erasing the original data from the data storage means at least after the data compression processing in the data compression means is completed Erasing means; elapsed time measuring means for measuring an elapsed time from when the original data is written to the data storage means; and compressed data for making the original data identical according to the elapsed time measured by the elapsed time measuring means. Compression data erasing means for erasing data from the data storage means in ascending order of compression ratio. Data storage device. 2. A recording apparatus comprising: a recording area dedicated to collectively recording data having the same compression rate with respect to data compressed at a plurality of compression rates; and the recording area is divided into a plurality of blocks. 2. The data storage device according to claim 1, further comprising a data storage means capable of erasing the data in block units.