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Automated Teaching File and Slide Database for Digital Images

¹ Department of Radiology, Hospital of the University of Pennsylvania, Ground Floor Founders, 3400 Spruce St., Philadelphia, PA 19104.
² Department of Psychiatry, Hospital of the University of Pennsylvania, Philadelphia, PA 19104.

Received February 28, 2000; accepted after revision May 2, 2000.

 
Supported by the American Roentgen Ray Society Scholars Program 1999-2000.

Address correspondence to J. A. Maldjian.

Abstract

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OBJECTIVE. We developed an easy-to-use method for creating a searchable digital teaching file of CT and MR images.

CONCLUSION. We describe a method of creating a digital archive of interesting cases that is easy to implement and works on a commercially available workstation. A remote daemon polls for images transferred to the product film tool. It creates a tagged image file format (TIFF) digital archive of these images on any platform supporting file transfer protocol (FTP), operates in the background, and automatically generates a searchable index of case information in the database.

Introduction

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The creation of teaching files and slides of interesting cases is one of the more common tasks performed by all radiologists and radiology trainees. However, this task is also one of the more tedious chores we perform. Popular methods of creating teaching files include copying filmed cases, refilming selected images, manually photographing selected images using light stands, and even appropriating the original films. The advent of digital filmless departments should simplify this task. Unfortunately, this simplification remains an unfulfilled promise from many vendors of digital imaging workstations. Although all manufacturers will purport some state-of-the-art method of generating digital teaching files, this frequently remains an afterthought or an unimplemented option. From personal experience in a department that has had different types of digital workstations and purports to be almost filmless, the creation of teaching files and slides remains a manually intensive task. Even assuming the use of advanced computer skills and the capability of pulling desired images out of an encrypted DICOM (Digital Imaging and COmmunications in Medicine) database, the task of direct digital extraction remains arduous. In our institution, the high-tech approach to creating and saving digital images for slides and presentations involves a digital camera and a light box.

A system that creates digital teaching files should be easy to use, simple to setup, and provide a searchable database of the logged cases. This method should not duplicate the browsing, display, cropping, windowing, and leveling functions of the host's display workstation. Ideally, the system should depend on the native functions of the host, minimizing the retraining of staff, fellows, and technicians, who are all potential users of the system. The images must be automatically transferred to desktop computers (PC or Macintosh [Apple Computer, Cupertino, CA]) and must be viewable in any commonly available desktop software application.

In this paper, we describe a method to create a digital archive of interesting cases that works on any platform, is easy to implement, and works with the Advantage Windows workstation (General Electric Medical Systems, Milwaukee, WI). It is an extension of a method previously reported by Ernst et al. [1], and it is designed to work in a heterogeneous environment with many workstations. Our method creates a tagged image file format (TIFF) file digital archive of selected images on any platform (i.e., Macintosh, Windows [Microsoft, Redmond, WA], Unix, Linux) that supports file transfer protocol (FTP), operates in the background, and automatically generates a searchable index of case information in the database.

Materials and Methods

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The Advantage Windows workstation is a commonly used image display workstation that also provides postprocessing tools. The Advantage Windows workstation is a Unix-based workstation operating off an UltraSPARC platform (Sun Microsystems, Mountain View, CA). The workstation provides an image display widget and a filming widget known as the film composer. Images can be filmed by dragging the image from the display widget (i.e., window) onto a panel in the film composer using the mouse. Printing is accomplished by selecting the print icon. As each image is dragged into the film composer, a flat-file digital image is stored in the film subdirectory on the workstation. These images are 8-bit 512 x 512 integer files without image headers; they are not DICOM [2] images, but they contain the windowing and leveling that was determined by the user before they dragged the images to the film composer. When the film composer is cleared, the files are automatically deleted from the film subdirectory.

The method we developed uses another Unix workstation (called a proxy FTP server) that polls the film subdirectory on the workstation for incoming image files. The proxy FTP server transfers the 8-bit headerless images onto a local database, converts them to TIFF files, and sends the images to the desired client computer (Fig. 1).

View larger version (87K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1. —This schematic shows image acquisition. When startftp command on Advantage Windows workstation is invoked, proxy file transfer protocol (FTP) server initiates IDL_FTP graphical user interface (GUI) via Xwindows connection. Proxy FTP server polls film directory on Advantage Windows workstation for images that were dragged by user to film composer. These images are sent to proxy server, converted to tagged image file format (TIFF) images within IDL (Research Systems, Boulder, CO), and then sent to client computer (i.e., Macintosh [Apple Computer, Cupertino, CA] or PC). Searchable patient database text log is automatically created and updated on both proxy FTP server and client computer reflecting patient information, folder location, and number of images transferred.

Configuring the Advantage Windows Workstation
The only program that resides on the Advantage Windows workstation for this application is a small shell script (startftp), which can be invoked from a command window on the Advantage Windows workstation. The script performs several tasks: it enables local display on the Advantage Windows workstation from the proxy server via the xhost command, it creates a small file (callerid) with the hostname of the Advantage Windows workstation, it executes a remote copy of the callerid file to the proxy server, and it invokes a script (startidlftp) on the proxy FTP server via the Unix rshell command.

Configuring the Proxy FTP Server
The proxy FTP server is a Unix-based workstation with Interactive Data Language (IDL) (Research Systems, Boulder, CO) installed. An IMAGE_ARCHIVE directory must be present in the home directory. A local archive of images is kept on the proxy server in the IMAGE_ARCHIVE directory of all FTP transfers. This can be a link to an external drive with ample memory for storing cases. The IDL programs for the IDL_FTPer and two shell scripts reside in the home directory. The shell scripts include the proxy FTP script that performs the FTP commands with appropriate command line inputs and a startidlftp script. The proxy FTP script is called from within IDL whenever files are to be transferred between machines. The startidlftp script is called remotely by the Advantage Windows workstation when the startftp command is invoked.

The startidlftp script on the proxy FTP server checks for a callerid file and initiates an Xwindows connection via an iconified Xterminal window on the Advantage Windows workstation, which called up the program. This opens IDL and starts the IDL_FTP Graphical User Interface (GUI) (Fig. 2) on the Advantage Windows workstation. Note that IDL does not reside on the Advantage Windows workstation, but rather, it is being executed on the proxy FTP server and displayed on the Advantage Windows workstation. IDL_FTP starts an FTP license server daemon (written in IDL specifically for this application), which creates a unique license file on startup containing the Advantage Windows workstation host name within its filename (i.e., FTP_license_Awneurol_24334). It also deletes any prior license files that originated from the same Advantage Windows workstation. The license daemon periodically checks for the presence of this license file. If it is not detected, it automatically shuts down IDL and terminates the Xwindows connection. In this way, multiple copies from the same Advantage Windows workstation are prevented from running.

View larger version (144K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2. —IDL_FTP graphical user interface opens on Advantage Windows workstation when startftp command is entered. Hostname, user, and password are entered for client computer to which images are to be automatically transferred. Fields are present for patient name, ID, diagnosis, and history. New folder with time—date stamp is created on desired client. As images are dragged into film composer on Advantage Windows workstation, corresponding tagged image file format images are automatically transferred to desired client.

Configuring the Image Archive Client
The client for storing the image archive can be any computer supporting incoming FTP connections that is accessible to the proxy FTP server. All Unix- and Linux-based machines support FTP as part of their operating system. Macintosh computers can accept incoming FTP connections using a $15 shareware program called NetPresenz 4.1, which can be down-loaded over the Internet (support@stairways.com). Configuring a Macintosh using this program is straightforward and simple. For housing the image database, a folder is created called IMAGE_ARCHIVE. IDL_FTP expects this folder to be in the root directory of the FTP user. For Macintosh systems, file sharing must be on, and the IMAGE_ARCHIVE folder must be shared, with the expected user having full read—write privileges. Similar programs are available for computers that run Windows, and the expected directory structure is identical.

IDL_FTP GUI
When the startftp script is initiated on the Advantage Windows workstation, the IDL_FTP GUI will open via an Xwindows connection to the FTP server. It displays entries for hostname, user, and password. These refer to the client (i.e., Macintosh) to whom the images will be sent. The client can be any computer that can accept FTP connections and is reachable by the proxy FTP server. Additionally, fields are displayed for patient name, ID number, diagnosis, and history. Although these fields are optional, they are useful for later cataloging the image archive. The GUI also displays a time-out counter, which defaults to 10 min of inactivity before shutting down the GUI and terminating the connection. This process prevents IDL_FTP from remaining active indefinitely, in the event that the user inadvertently forgets to manually quit the session or physically leaves the Advantage Windows workstation. When the startup button is pressed, IDL_FTP (residing on the proxy FTP server) attempts a connection to the desired client via the Packet Internet Groper (PING) command. If the client is online, the proxy FTP server tests the FTP connection. If this test checks out, the proxy FTP creates a new directory on the client machine with the patient name and a unique time—date stamp. This file is created in the IMAGE_ARCHIVE subdirectory of the client machine. Then the proxy FTP server begins polling the film subdirectory on the Advantage Windows workstation for any images. When an image is detected, it is transferred to the proxy server and converted to a TIFF file within IDL, and then the program sends the image to the client workstation. Additionally, two beeps are heard indicating that a file has been detected and transferred. If a repeated filename is detected, a unique filename is generated before transfer. A text file log is updated within each subdirectory that lists the patient information provided to the IDL_FTP GUI, transfer date, and the names of the images transferred. A master patient log is automatically updated within the Patient_Data subdirectory that lists all the patients in the IMAGE_ARCHIVE, patient information provided to the GUI, and the names of the subfolders in which the patient images can be found. Figure 3 shows the directory tree for some sample cases sent to a Macintosh computer.

View larger version (57K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3. —Screen capture shows Image Archive Directory (left) and log file (right) with cases that are automatically transferred into unique folders containing tagged image file format (TIFF) images and patient log (PT_DATA), which lists patient information provided by user. PTDATA_MASTER file is automatically updated with case information and patient folder name.

Polling can be suspended by pressing the shut down button. To begin transferring data on a new case, information is updated in the patient information fields, and the startup button is pressed. A unique folder is automatically created with its own time—date stamp, and the case log files are appropriately updated. IDL_FTP is designed to automatically shut down after 10 min of inactivity. If the startftp script is inadvertently initiated while a session is running, the FTP license daemon will automatically shut down the previous session to prevent multiple instances of IDL_FTP from running. However, IDL_FTP will permit multiple sessions from different Advantage Windows workstations to run simultaneously.

Security
Radiology departments are well aware of potential security breaches and are careful to place patient-sensitive imaging data behind a firewall (our department is no exception). This process prevents unauthorized users from outside the institution from gaining access. The proxy FTP server that we use, as well as the Macintosh and PCs that serve as the image archive database, are behind this firewall. The proxy FTP server must be behind the firewall to communicate properly with the Advantage Windows workstation; however, it is possible for a client machine, such as a Macintosh or PC, to be outside the firewall by enabling an outboundonly FTP connection. Such an implementation would require the input of the information technology specialist for the network.

System Performance

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Out system has been implemented in the neuroradiology section of our department for 2 months. It has been used primarily by our neuroradiology fellows and some of our attending staff. The learning curve is minimal, and transfers are unobtrusive to normal function in the reading room. After transferring approximately 100 cases, we noted only three failures (i.e., partial transfers) to the client computer (Power Macintosh G3; Apple). Because our client workstation is used by our entire section for a wide variety of tasks (image processing, document scanning, printing slides, etc.), partial transfers are usually related to operating system crashes from other applications. However, all cases were logged and transferred in their entirety onto the archive on the proxy FTP server (which maintains a backup image archive of all transfers).

Discussion

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We describe a simple method of creating a digital teaching file of interesting cases. The method was designed to be as unobtrusive as possible, adding a minimum of steps to what is currently used. Many of our staff members and fellows currently use the film composer of the Advantage Windows workstation to select and generate films of interesting cases. They require no additional training to use the facility. The method we describe works with the Advantage Windows workstation to operate in the background while images are selected for filming. Most of the programs are written in IDL. Although a new purchase of IDL can cost approximately $1500 for a single user license, IDL is a commonly used image processing language and is already available in many radiology departments. A similar method can be implemented using C programming routines, which would obviate purchasing IDL. In our implementation, all images are converted to TIFF files, a widely available format recognized by most modern software programs. Additionally, IDL_FTP automatically creates a database and catalogue of the cases in the archive. Because the log is a text file, it can be easily searched for specific entries. Furthermore, all the fields in the master log are delimited by a characteristic text string, making it relatively straightforward to import the log into any popular database program. Many methods for image storage are available, including CD-R/ROM, which can offer an efficient and cost-effective method of providing a digital teaching file for staff and trainees. Until image workstation vendors make good on their promises of teaching file compatibility, this method is a reasonable approach to solving a common time-consuming problem. A copy of the routines described in this paper can be obtained by contacting the author via e-mail (maldjian@oasis.rad.upenn.edu).

References

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1. Ernst R, Kawashima A, Tamm E, Sandler C. A high-quality, low-cost, internet/intranet-based digital imaging database. RSNA Electronic Journal page. RSNA Web site. Available at: http://ej.rsna.org/EJ_0_96/0056-97.fin/. Accessed September 6, 2000
2. Bidgood WD Jr., Horii SC. Introduction to the ACR-NEMA DICOM standard. RadioGraphics 1992;12:345 -355[Abstract]

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This Article Abstract Figures Only Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Maldjian, J. A. Articles by Listerud, J. Search for Related Content PubMed PubMed Citation Articles by Maldjian, J. A. Articles by Listerud, J. Social Bookmarking                      What's this?