JP2000067136A - Medical imaging communication system - Google Patents

Abstract

(57) [Problem] In a conventional medical image communication system for transmitting and receiving medical image information between a plurality of hospitals connected to a network, there is a problem in the level, management and processing speed of digital medical image display. SOLUTION: For displaying a medical image on a display 3 (or 4), a gradation conversion circuit 5, a frame memory 2, a digital / analog conversion circuit 6 and a memory 7 are provided. The memory has a constant ratio with the luminance, the memory accumulates the image data so that it can respond to the display request at a high speed, and the frame memory enables the display of three or more images in association with each other. This includes using the display for doctors' teleconference devices and e-mail, using a network as a connectionless dedicated line that eliminates information leakage, and centrally managing images for each hospital in a database.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medical image communication system capable of centrally managing medical images generated in a plurality of medical facilities and displaying images at high speed.

[0002]

[Prior Art] (From film and photographic media to electronic media)
The images used in medical practice are X-ray images, CT images, M
There are a wide variety of images, such as RI images, pathological images, endoscopic images, and ultrasonic images. Transmission, storage, and storage of these medical images have been performed in different forms depending on the acquisition form of each image.

For example, since an X-ray image is recorded on an X-ray film and the film is placed on a viewer called a Schaukasten to observe the image, it has been necessary to send, store and store the X-ray film itself for many years. Has been done.

[0004] For example, a pathological image is obtained by staining a tissue or cell of a human body and displaying it in an enlarged manner under a microscope. For accumulation and preservation, a sample body preparation or a photograph of a microscope image is sent, and accumulated and stored. Was. For other medical images, almost the same transmission, storage, and storage methods using films, photographs, and the like have been adopted.

[0005] With the recent improvement of computers and their peripheral technologies, the digitization of medical images, which are used to convert these medical images into digital data by using a scanner or the like, is spreading rapidly. The medical image converted into digital data is stored and stored in an electronic memory medium (semiconductor memory, magnetic memory, magneto-optical memory, etc.), and displayed on a computer display as needed. In addition, the transfer of these medical image data to and from hospitals via a communication network has become easier and more economical as the digital communication network is improved.

[0006] As described above, with the advance of the digitization of medical images and the development of digital networks, it becomes possible to transfer medical images instantaneously irrespective of location and time. Various forms of medical services using are becoming real. With the advent of such new medical forms using digital communication networks, the convenience of doctors and patients can be significantly improved. .

(Conventional Medical Image Communication System) FIG. 10 shows a conventional configuration of a medical image communication system. The figure shows
The drawing illustrates a case where medical image capturing devices, medical image display devices, medical image databases, and the like installed in a plurality of hospitals A, B, and C are connected to each other via a communication network. Each hospital is connected with a digital medical image acquisition device such as a film digitizer and a CT imaging device, an image display device, a database, and the like via an in-hospital LAN. Also,
The hospital LAN is connected to a communication network connecting hospitals via a communication terminal device (DSU).

At each hospital, diagnosis is performed by displaying a digital medical image obtained by the medical image acquisition device on an image display device. Further, the digital medical images acquired in the hospital are stored in a database, and are searched and displayed from the medical image display device as needed. What is used as an image display device is a terminal combining a computer and a computer display. From this terminal, access processing to the database, medical image display, and the like are performed centrally.

The transfer of medical images via a communication network connecting hospitals is performed by transferring and displaying images when a patient moves from one hospital to another or when the hospital needs more specialized diagnosis. It is carried out when it is. In such a case, the medical image stored in the database device placed in each hospital is taken out, and the image data is transferred to the destination hospital via the network. By doing so, what has been conventionally mailed with a radiation film or a photograph is electronically transferred via a network, so that high-speed image transfer is possible.

First, a medical image transfer request is transmitted from a medical image receiver having a medical image display device to a medical image database. A medical image sender having a medical image database retrieves desired image data from the database based on a medical image transfer request, and sends the retrieved image data to a communication network. The medical image receiver receives the image data from the communication network and displays it on the image display device.

The data transmitted and received via the communication network includes medical images such as radiation images and information associated therewith, that is, examination dates, examination medical facilities, patient IDs, patient names, patient birth dates, sex, examinations, and the like. The information includes a device, diagnostic information, a test site, a laboratory technician name, a diagnostic doctor name, and the like.

The data format of medical image information including such accompanying information is described in ACR-NEMA.
(The American College of
Radiology and the Nationa
l Electrical Manufacturer
s Association) and the like. Usually, data is exchanged in a standardized medical image format.

[0013]

In a conventional medical image communication system, image data corresponding to the gradation of a display device is created at the time of acquiring image data in order to reduce the amount of data transferred through the communication network. In that case, it was difficult to individually perform gradation conversion in the image display device in accordance with the performance of the display device, and there was a sense of incongruity in display between the film image and the display image.

[0014] Also, because it is difficult to ensure security,
It was difficult to share an image database among multiple hospitals.

Furthermore, since the image is transferred from the database every time a display image is requested, there is a problem that the amount of data flowing through the communication network increases and the image display time increases.

An object of the present invention is to provide a medical image communication system for transmitting and receiving medical image information between a plurality of hospitals connected to a network, which is capable of displaying a medical image at a level having no problem in image display on a display. An image communication system is provided.

It is another object of the present invention to provide a medical image communication system capable of economically storing and managing medical image information by centrally managing medical images of a plurality of hospitals in one database. It is in.

Still another object of the present invention is to provide a medical image communication system capable of performing high-speed image acquisition and display via a network.

[0019]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides the following medical image communication system.

(First Invention) In each hospital, a medical image acquisition device for obtaining a digital image from a film medical image and a medical image display device are connected via an in-hospital network, and medical image information can be exchanged between hospitals at high speed. Network connection, the medical image display device is a medical image communication system including a gradation conversion means, wherein the gradation conversion means, the brightness of the film image and the brightness of the image displayed on the image display device It is characterized by having a gradation conversion function that makes the ratio constant.

(Second Invention) The image display device has a memory for storing a plurality of image data input via a network, and when there is a request for displaying the image stored in the memory. Means for reading and displaying data from the memory.

(Third invention) The image display device has a frame memory capable of storing three or more image data,
Means for reading out and displaying data from the frame memory when an image display request stored in the frame memory is requested.

(Fourth invention) The image display device is characterized in that the image display device is provided with a teleconference device and / or e-mail communication means for communication via the network.

(Fifth invention) The network connecting the hospitals is characterized by using a connectionless dedicated line.

(Sixth invention) A database for centrally managing medical image information obtained at each hospital via a network connecting the hospitals is provided, wherein the database is prepared for each hospital registered in advance and for each doctor at the hospital. An access control unit for setting an access right for obtaining medical image information and setting an access right for each medical image information is provided.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) (Medical image communication system using an ultra-high definition image display system for displaying medical images and having another display for displaying accompanying information) FIG. The image display section is shown enlarged.
The image display unit includes a data control terminal 1 having a computer configuration,
It comprises a frame memory 2, a display 3 for displaying medical images, a display 4 for displaying accompanying information and a system control screen.

The medical image data and the accompanying information input to the image display unit are first displayed on the accompanying information display 4. The medical image data is input to the high-definition medical image display 3 via the frame memory 2 and displayed.

The display 3 for displaying a high-definition medical image includes:
The display is capable of displaying an image with a pixel count of 2000 × 2000 or more, a gradation of 8 bits or more, and a frame frequency of 60 Hz or more.

Medical images, especially radiation images, are required to have high resolution. In order to display one image on one display, it is necessary to use a high-definition display having at least the above characteristics. Frame frequency is 60Hz
With the above, the flicker noise becomes an area below the limit of human perception, and even if the doctor stares for a long time for diagnosis, an image display without a sense of incongruity is possible.

As described above, of the medical image information, the accompanying information is displayed on the computer display 4 and the image main body is displayed on the display 3 which is a high definition image display device.

By adopting such a configuration, conventionally, a database search, an image, and display of accompanying information are conventionally performed on a single display.
Although it was necessary to switch the image display area, according to the present embodiment, there is an advantage that such an operation on the display surface is simplified. Further, by using a device having a pixel number of 2000 × 2000 or more, a gradation of 8 bits or more, and a frame frequency of 60 Hz or more as a display device of the image body, it is possible to display an image having a resolution sufficient for image diagnosis.

(The network communication speed does not limit the display time of the apparatus, and the network speed is limited to keep the display time within 20 seconds.) FIG. 2 shows the data transmission speed of the network connecting the hospitals and the network. Is a measurement value indicating the relationship with the time until image data is acquired via the PC and the medical image is displayed on the image display device.

In order for a doctor to perform an operation of obtaining and displaying a medical image from a remote place in near real time, the time required from the image request to the image display must be within 20 seconds. From the measurement results in FIG. 2, it can be seen that the network speed needs to be 5 Mbps or more in order to reduce the time required from the image request to the image display to 20 seconds or less.

Therefore, in the medical image communication according to the present embodiment, the speed of the network connecting the hospitals is set to at least 5 Mbps. There is a trade-off between the reduction in display time due to the increase in network speed and the cost of a system that satisfies this requirement. By setting the network speed to at least 5 Mbps, a near real-time medical image communication system can be realized economically. Physicians' requirements for image display time are various. If a faster display time is required, a network speed corresponding to the request may be selected within a range of 5 Mbps or more.

Conventionally, for example, a telephone line (transmission speed 64 k
Even transferring medical images using bp) took several hours. In such a system, the image is transferred at midnight or the like, and although the speed is higher than in the past when the film was mailed, it was not real time. According to the present embodiment, there is an advantage that a near real-time medical image transfer display can be realized.

(Medical Image Communication System for Performing Gradation Conversion Processing Immediately Before Image Display) FIG. 3 shows an image display apparatus provided with a gradation conversion circuit 5 at a stage preceding a high definition display for medical image display.

The gradation conversion circuit 5 converts 10-bit to 12-bit gradation image data stored in the database into gradation data in consideration of the characteristics of the image display 3 and the displayable gradation. is there.

As described above, by adopting a configuration in which the gradation conversion processing is performed immediately before displaying an image, there is an advantage that the entire system can be adapted to various display devices.

It is to be noted that the gradation conversion circuit 5 can be provided in a stage preceding the display for displaying the accompanying information.

(Medical image communication system in which gradation conversion processing uses luminance linear conversion method) FIGS. 4A and 4B show a case where a conventional radiation film is placed on a light box called a Shakasten to display an image and a case where a digital image is displayed as in this embodiment. This is compared with a case where an image is displayed on a display.

When an image is displayed by placing a conventional radiation film on a light box, light transmitted through the film is observed. The radiation film performs image recording by utilizing the property that the film is blackened by radiation irradiation and the light transmittance is reduced. The degree of blackening of the film is called the film density, and the higher the film density, the lower the light transmittance and the lower the brightness. The relationship between the film density and the light transmittance or the brightness of the display image is expressed by the following equation.

[0042]

L _f = L _in 10 ^-D (1) In the above equation, L _f is the luminance of the film, L _in is the luminance of the light source (sharksten) placed on the back of the film,
D (0 <= D <= Dmax) represents the film density, respectively.

The image data obtained by converting the image having the display characteristics represented by the equation (1) into a digital image by a film digitizer or the like has a linear pixel value with respect to the film density. At this time, the digital value is Nf bits, and the pixel value is Xf (d0 <= Xf <= d1, d
1 = 2 ^Nf -1).

The gradation conversion circuit 5 of this embodiment makes the ratio between the luminance of the film image and the luminance of the image displayed on the display always constant. In this case, it is necessary to convert a pixel value having a linear value with respect to the film density in consideration of the input / output characteristics of the display.

When the image display 3 is a CRT, the relationship between the input voltage and the displayed luminance is non-linear, and is known as the γ characteristic. The relationship between an input signal and luminance in a CRT display is expressed by the following equation.

[0046]

(Equation 2)

[0047] Here, Lc is the luminance, L ₀ is the luminance when the input voltage to the CRT is 0, a is a constant, Xc (0 <= Xc <
= D2) represents the digital value of the pixel, and γ represents a value specific to the CRT display.

Using the expressions (1) and (2) and the condition that the output luminance ratio is constant, the following gradation conversion function can be obtained.

[0049]

(Equation 3)

Here, g ₂ is a conversion function, and L _max is a CRT.
Respectively represent the maximum luminance of. By converting the digital image data of the film density linear according to the equation (3), the ratio of the luminance displayed on the display to the luminance of the film can be made constant.

As described above, if the luminance ratio between the two is linearized, the image on the display and the film image look the same without any discomfort to the image observer from the viewpoint of human vision. As is clear from equation (3), the conversion equation depends on the display characteristics such as the maximum luminance and the γ value of the display. If the function of measuring these values and changing the parameters is added to the gradation conversion circuit 5, the above-mentioned gradation conversion can be used for any display. Further, in order to speed up the gradation conversion processing, a look-up table (LU
T) may be created, and conversion may be performed by sequentially referring to the LUT when image data is input.

As described above, according to the present embodiment, there is an advantage that the medical image displayed by the medical image display device can be viewed in the same way as the medical image display on the film. As a result, it is possible to display an image that can be used for medical diagnosis.

(Second Embodiment) FIG. 5 shows a configuration around a medical image display device. The medical image input to the medical image display device is converted into a gradation conversion circuit 5, a frame memory 2, a DAC,
(Digital-to-analog conversion circuit) 6 to the high-definition image display 3.

In this embodiment, a memory 7 for storing medical image data is provided before the gradation conversion circuit 5. The memory 7 has a capacity capable of storing a plurality of medical image data, and when exceeding a preset capacity, erases the oldest stored image data and stores new image data. .

The memory 7 used here may be a nonvolatile memory. In particular, when the network bandwidth is small, it is difficult to repeatedly access and read the same data via the network. In the nonvolatile memory, the information is not erased even when the power of the image display device is turned off (even when the power is turned off). When the image display device is restarted, the information stored and held in the memory is taken out. Can be displayed.

The image display device is usually placed in a doctor's examination room or a reading room. In such a case, it is common for a doctor to issue a test request for a patient to be examined, and to perform a medical examination relative to the patient while looking at a medical image as a test result after the examination is performed. In this case, it is desirable that an image acquired by a medical image acquisition device such as an X-ray examination device be displayed on the image display device of the doctor in charge immediately thereafter.

In the present embodiment, the image acquisition device transfers and registers the acquired image in the medical image database, and simultaneously transfers and stores the medical image data in the memory 7 of the image display device of the doctor in charge.

When a doctor reads an image from the medical image database and displays the image on the image display device, the medical image transferred from the database is guided to the gradation conversion circuit and stored in the memory 7. . When the doctor once displays the displayed image again, it is checked whether or not the corresponding medical image data is stored in the memory 7, and if not, the image data is transferred from the medical image database. I do. The doctor requests the image display in real time in the case where the image immediately after the examination is read from the database and the image displayed once is displayed again for confirmation as described above.

According to the present embodiment, when such a real-time image display is required, the image data stored in the memory 7 provided in the image display device is read out and displayed. And the processing time associated with it.

Therefore, according to the present embodiment, even if the medical image database is located at a remote place, the doctor can display necessary medical images in real time.

That is, in the present embodiment, the workstation has a cache and caches the medical image obtained immediately before via the network, thereby realizing effective use of the network and high-speed image display.

(Third Embodiment) FIG. 6 shows another embodiment of the present invention, in which the number of image data that can be stored in the frame memory 2 is three or more.

When the medical image data is input to the image display device, a gradation conversion process is performed by the gradation conversion circuit 5, and the gradation-converted image data is temporarily stored in the frame memory 2. A DAC (digital-to-analog conversion circuit) reads data from the frame memory at a reading speed corresponding to the performance of the display, converts the data into an analog signal, and then transfers the data to the high-definition display 3.

The time from when the image data stored in the frame memory 2 is input to the display until it is displayed is generally so fast that a human cannot recognize it. On the other hand, when the data amount of the image data increases, the time required for the gradation conversion processing increases. Therefore, when displaying medical image data with a large resolution, the time required for the gradation conversion processing becomes a problem. The doctor observes about three images for one patient. This is a plurality of images of the same part of the same patient in different imaging directions, or an image of a plurality of parts. The doctor repeatedly displays the image of the patient, observes the image, and makes a diagnosis. In that case, higher-speed image display is required.

In this embodiment, data of one patient is
By storing more than one image data in the frame memory 2, high-speed image display is realized.

As described above, according to the present embodiment, by setting the number of pieces of image data that can be stored in the frame memory to three or more, a high-speed image display that does not cause a doctor to feel uncomfortable can be realized.

That is, since the frame memory stores a plurality of frames, a plurality of images displayed immediately before can be displayed at higher speed. The three grounds are
This is based on the need to display at least three images per patient at high speed, such as front, side, and other parts, for a chest radiographic image.

(Fourth Embodiment) FIG. 7 shows a medical image display device according to another embodiment of the present invention. In the present embodiment, a video conference system 8 and / or an e-mail system are provided in addition to the image display device.

Both the video conference system and electronic mail can be communicated between a plurality of medical image display devices connected to a network. Therefore, a video conference switch and an e-mail server are provided in the network.

The medical image communication system has a function of transferring, storing, and displaying medical images, and providing consultation for doctors at different hospitals to examine cases and make diagnoses while observing the same medical images. Law is conceivable. When the medical image communication system provides such use, communication means between doctors is required.

The present embodiment is characterized in that a video conference system or an electronic mail system is provided as a communication means.

By providing a video conference system,
Doctors can discuss the medical diagnosis through voice while confirming each other's facial expressions and the like. In addition, if an e-mail system is used, the doctor does not need to perform image observation on the medical image display device at the same time, but can transmit necessary information regarding diagnosis and the like by e-mail so that necessary consultation and Case study becomes possible. At this time, the medical image to be targeted may be displayed by searching for the necessary medical image from the medical image database based on the information written in the e-mail.

As described above, according to the present embodiment, the medical image display apparatus has the advantage that the case examination and the diagnosis support can be performed by providing the communication means between the doctors at the remote locations. That is, it is possible to provide a means for doctors to communicate with each other when a conference or the like is performed.

(Fifth Embodiment) FIG. 8 shows another embodiment of the present invention, in which a connectionless dedicated line network 9 is provided as a network for connecting hospitals.

Connectionless type private line network 9
ATM (Asynchronous Tran)
sferMode) network in the PVC mode. IP (Internet Protocol)
ol) By connecting, communication with the connection device becomes possible without being conscious of the inter-hospital network. Also,
Since a dedicated line is used, information transmitted and received via the network does not leak to others, and highly reliable communication can be performed.

As described above, according to the present embodiment, the connectionless leased line network 9 is used for connecting between hospitals.
By using, communication with high security and a high degree of freedom is possible.

That is, the present invention is characterized in that a dedicated line is used for ensuring security, and a connectionless network is applied to enable free access.

(Sixth Embodiment) FIG. 9 shows another embodiment of the present invention, in which a medical image database 1 of a data management facility in which medical image information of a plurality of hospitals is connected to a network.
0 is a unitary management.

In order to ensure the security of medical image information for each hospital, each hospital or a doctor in each hospital has a means for registering a user in the database. The database 10 has a function of restricting access so that only registered users can access medical image information. This access restriction is performed for each medical image information.

When a doctor at hospital A obtains a medical image from the database, for example, there is a method of accessing the database by inputting a registered name and a password when accessing the database 10. If the security is not sufficient with a normal password, there is also a method of using a one-time password that changes the password each time it is accessed.

In the database 10, medical image information is managed for each hospital, and access is restricted. For example, a doctor at hospital A can access only the medical image information of hospital A stored in the database. This access right can be changed for each image by a medical image holder (mainly a doctor) for each image.

For example, a doctor a of a hospital A becomes a doctor b of a hospital B
When the doctor a wants to consult about the case of the patient c, the doctor a can grant the doctor a the right to access the medical image information of the patient c registered in the database 10. In this case, it is possible to access the medical image of the hospital A while staying at the hospital B.

The change of the access right can be set separately for a temporary one and a permanent one. Since the access right is given for each doctor, the doctor at the hospital A can also refer to the medical image information at the hospital A using the image display device at the hospital C. Depending on how hospitals manage medical information,
Even if a doctor at the hospital does not have access to medical image information outside the hospital, access restrictions can be set.

As described above, in this embodiment, the medical image information of a plurality of hospitals is centrally managed by a database connected to a network. This makes it possible to centrally perform the storage management of electronic medical image information, which was conventionally performed after securing the location, equipment, and maintenance personnel for each hospital. Expenses can be greatly reduced.

Further, since the database can execute the user registration means and the access restriction function based on the user registration information for each medical image information, there is an advantage that the security of the medical image information can be secured for each hospital or each doctor. is there.

Therefore, according to the present embodiment, there is an advantage that storage management of medical image information can be realized economically and safely.

That is, the medical image information of a plurality of hospitals is centrally handled, and access is restricted so that the medical image information is not leaked between hospitals.

[0088]

As described above, according to the present invention, as a gradation conversion means for displaying on a display, the ratio between the luminance of the film image and the luminance of the display image is kept constant. The medical image can be made to have the same appearance as the medical image display on the film, and a medical image display having a sufficient resolution for diagnosis can be obtained.

Further, according to the present invention, by providing a memory for temporarily storing image data which is likely to be displayed in the image display device in accordance with the usage form of the doctor, the use image can be displayed at high speed. I have. This prevents the same image data from being repeatedly transferred on the network at the same time, and has an effect that network resources can be effectively used.

Further, the medical image information of a plurality of hospitals is centrally managed while securing the confidentiality of the medical information in one database, so that the preservation and management of medical images can be realized economically. There is.

Although the present invention is based on the premise that medical image information of a plurality of hospitals is transmitted / received via a network, displayed, stored and managed, it is necessary to communicate a large amount and large amount of image information at high speed and safely. It can be applied to other applications.

[Brief description of the drawings]

FIG. 1 is a detailed view of an image display device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a data transmission speed characteristic of a network according to the first embodiment of the present invention.

FIG. 3 is a gradation conversion circuit according to the first embodiment of the present invention.

FIG. 4 is a view for explaining gradation conversion characteristics according to the first embodiment of the present invention.

FIG. 5 is a detailed view of an image display device according to a second embodiment of the present invention.

FIG. 6 is a detailed view of an image display device according to a third embodiment of the present invention.

FIG. 7 is a detailed view of an image display device according to a fourth embodiment of the present invention.

FIG. 8 is a diagram illustrating a network configuration according to a fifth embodiment of the present invention.

FIG. 9 is a database configuration diagram showing a sixth embodiment of the present invention.

FIG. 10 is a configuration diagram of a conventional medical image communication system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Data control terminal 2 ... Frame memory 3 ... Display for medical image display 4 ... Display for incidental information and system control screen display 5 ... Gradation conversion circuit 6 ... Digital / analog conversion circuit 7 ... Memory 8 ... Video conference device (electronic 9) Connectionless leased line network 10 ... Medical image database for centralized management

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 5/00 510 G06F 15/40 310F 5/36 520 370B H04N 1/407 15/68 310J // G06T 1 / 00 H04N 1/40 101E G06F 15/62 390Z (72) Inventor Junji Suzuki 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Akira Okumura Nishi-Shinjuku, Shinjuku-ku, Tokyo 3-19-2 Nippon Telegraph and Telephone Corporation (72) Inventor Isao Furukawa 3-19-2 Nippon Telegraph and Telephone Corporation 3-72-2 Nippon Telegraph and Telephone Corporation (72) Inventor Sadayasu Ono Nishi-Shinjuku, Shinjuku-ku, Tokyo 3-19-2 Nippon Telegraph and Telephone Corporation F-term (reference) 5B057 AA08 AA09 CA02 CA08 CA12 CA16 CB02 CB08 CB12 CB16 CC01 CE11 CH07 5B 075 KK07 KK13 KK33 KK54 ND06 PP03 PQ02 PQ12 UU29 5C077 LL18 MP01 NN02 NP03 PQ23 RR06 5C082 AA04 AA36 AA37 BA12 BA20 BA39 BB01 BB15 CA84 DA87 DA89 MM02

Claims (6)

[Claims] 1. In each hospital, a medical image acquisition device and a medical image display device for obtaining a digital image from a film medical image are connected via an in-hospital network, and each hospital is connected to a network capable of exchanging medical image information at high speed. Wherein the medical image display device is a medical image communication system including a gradation conversion unit, wherein the gradation conversion unit has a constant ratio between the luminance of the film image and the luminance of the image displayed on the image display device. A medical image communication system having a gradation conversion function. 2. The image display device according to claim 1, further comprising: a memory for storing a plurality of image data input via a network, wherein when a request for displaying the image stored in the memory is issued, the image data is output from the memory. 2. The medical image communication system according to claim 1, further comprising means for reading out and displaying. 3. The image display device has a frame memory capable of storing three or more pieces of image data, and reads and displays data from the frame memory when an image display request stored in the frame memory is requested. 3. The medical image communication system according to claim 1, further comprising: 4. The image display device according to claim 1, wherein the image display device includes a video conference device and / or an e-mail communication unit for communication via the network. Medical imaging communication system. 5. The medical image communication system according to claim 1, wherein the network connecting the hospitals is configured using a connectionless type dedicated line. 6. A database for centrally managing medical image information acquired at each hospital via a network connecting the hospitals, wherein the database includes medical image information acquisition for each hospital registered in advance and for each doctor at the hospital. The medical image communication system according to any one of claims 1 to 5, further comprising an access restriction unit that sets an access right for each of the medical image information and sets the access right for each medical image information.