Invited Symposium: Computing in Surgical Pathology
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Introduction
Telepathology has acquired in the last years considerable development and diffusion. Some complex equipments allow real time video sequences transmission and even remote interaction with the emitting microscope. These systems of high quality present essentially two limitations. First its high cost, specially at the time of having lines with enough bandwidth to support the transmission of high quality video. The second limitation is that they are in general, of closed systems. The communication establishes between two points, or among a small network of nodes where the special communication lines have been located.
In order to surpass these limitations we have developed a telepathology system with two basic characteristics: its simplicity and low cost, and its limitless application practically to any pathologist of the world through Internet network. We used as origin of the communications a conventional computer connected to a microscope, and with the only addition of a video camera to obtain the images, and a video capture card that incorporates them to the computer. The software employed is of gratuitous distribution (freeware) and low cost (shareware). The system tries to optimize image transmission through 33.6 Kb/s conventional telephone lines allowing to receive sequences of static images with a frequency of 1-2 per second.
System Description
Communications were maintained essentially between two computers. The receiver is potentially any computer connected to Internet. It does not need any specific software, since images arrive through the Internet browser. The emitting computer used was a PC with processor Intel Pentium to 166 MHz, with 64 Mb of RAM memory and three hard discs with 7.4 Gb of global capacity, and a 17" monitor. The operating system was Windows 95 (4.00.950a) and we had an Internet Server installation (Microsoft Personal Web server, version 4,02,0602) Images were obtained from a microscope Nikon Labophot 2A, with a color video camera Sony SSC-C370P, with 470 TV resolution lines and a 752x582 pixels sensor. The camera transmits the images to the computer through the capture card (ComputerEyes/PCI) inserted on a PCI expansion slot. Images are sent to a Web page designed in HTML format, located in the own computer, and accessible from Internet through the PWS.
click to enlarge
Fig. 1: Sreeen in the reciving computer with the Internet browser.
(Image: Breast Infiltrating Micropapillary Carcinoma)
The software that compresses the image to format jpg and sends it in
a continuous form to the designed web page, is Webcam32, version 4.7.1. a shareware with a price of $25 and that we obtained in the following Internet address: http://www.kolban.com/webcam32/
This program allows choosing image resolution until a maximum of
720x576 pixels. An important element of this program is the possibility of using the denominated server push technology, that allows updating images in a continuous form in the Internet browser of the receiving equipment as they are caught.
The emitting computer was connected to Internet through an ISDN with
two 64 Kb/s channels. One of the channels was employed for image
transmission whereas the other was used simultaneously to maintain
a telephone connection with voice with the receiver. All the receiving
computers in which the system was tested had conventional telephony
connections to Internet with 33.6 Kb/s data transfer capacity.
The system was used if the following way. Initially a voice telephone
connection between transmitter and receiver was established.
Both connect to Internet, and receiver types in the browser
the IP address of the server located in the emitting computer.
It leads to a Web page that has an image frame with 640x 480
resolution pixels. The screen of the emitting computer has
in a window the image that arrives directly from the microscope,
and in another window, with an Internet browser, the same page
where the images are sent, to verify exactly in real time what
the receiver is watching.
From the beginning of this decade diverse telepathology systems
have been developed. In some cases they came justified by geographic
necessities, or absence of pathologists in remote places, like
among the Norwegian pioneers in the development of these systems
in Europe. Diverse studies try to demonstrate the validity of the
pathologic diagnoses conducted by means of remote systems, even
for frozen studies. The heterogeneity of these systems does difficult
to establish global criteria of effectiveness. Specially when they
are not only influenced by technical factors of resolution or
quality in image transmission, but also by pathologist training
in handling and diagnosing with digital images.
The use of Internet network as telepathology transmission system
reduces the possibilities of high quality images interchange.
The rates of transference that conventional telephony lines allow
are about 33.6 Kb/s or 56 Kb/s in optimal conditions. With these
conditions it is impossible to use sequences of video in real time.
The sensation of movement in video is obtained with sequences of
around 25-30 frames per second. Although image compression
techniques have obtained great advances, video transmission
requires at least a triple ISDN, or better a quadruple ISDN with
bandwidths of 384 or 512 Kb/s. The use of Internet, with conventional
telephony lines forces to the use of static images in our system of
telepathology. The simplest way to make this, is to choose the images
to transmit, compressing them to a graphical format gif or jpg, and
to send them by e-mail to our addressee.
This is far from the ideal conditions of a telepathology system,
in which besides image quality an authentic interaction between
transmitter and receiver is very important. The system that we
have developed takes advantage of to the maximum the bandwidth
available in Internet. It is intended to use the 33.6 Kb/s
capacity in a continuous way. The graphical compression in format
jpg allows obtaining images with a resolution of 640x480 pixels,
maintaining quality acceptable, and of a size between 15 and 30 Kb.
Using smaller resolution, 320x200, 400x300, or 480x360 transference
rate can be even superior to two images per second.
This is not of course video sequences, but transmitting and receiving
up to two images (static) per second, supposes a spectacular
improvement in relation to receiving in our mailbox some unconnected
images. The software that allows the transmission in expressed
conditions is used extensively in Internet in the so-called WebCam,
nevertheless, we have not found a previous description of its
application to a telepathology system. In order to obtain to an
authentic communication between transmitter and receiver we have
chosen to dedicate completely Internet line to the image transmission,
while another voice telephone connection simultaneously is established.
The described system, still without having the benefits of the
complexes and expensive modern telepathology equipments, allows
to have in a extremely simple way, an effective procedure of
transmission of graphical information, of means of consultation
and discussion of remote cases, and all the applications that can
be developed through telepathology.
Click
to enlarge
Fig. 2: Sreeen in the emitting computer with the Internet browser
and webcam32.(Image: Solitary Fibrous Tumor of the Liver)
The simultaneous telephone connection allows a total interaction
and the studied case can be commented in real time as well as the
displacement of the slide in the microscope, the magnification,
or the resolution of the image. In case of having an ISDN, it is
possible to replace voice telephone connection, by a telephony
system in Internet (Netmeeting, Netscape Conference, Internet
phone, VDOphone...) through the second channel of the ISDN,
which lowers the cost of the connection as being made in a
local call way. Internet browser preferably used was Netscape
Navigator versions 3 or 4, which admit Server Push technology.
We designed an alternative Web page to work with MS Explorer
navigator, were imaged replacement was settled with a Java applet
or a code in dynamic HTML.
The code necessary to generate Web pages is extremely simple.
The fundamental aspect is specifying server address and port
through which the images are sent and that have to agree with
the specified in the settings of Webcam32 program.
The use of an own Internet server for the shipment of the images
is not essential. It has been used exclusively to reduce to the
minimum the distance that crosses the images between transmitter
and receiver. The system also works sending the images from the
emitting computer to a Web page located in any Internet server.
Discussion
References
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