The ultimate goal of this German regional stroke unit pilot project is to establish a state-wide competence network across Rhineland-Palatinate and to connect other regions, such as in the State of Baden-Württemberg, as well. The official request for proposals, won by Steinbeis, was organised by Pergis, a health care consultant company, located in Ludwigshafen, and by a group of subcontracted teleradiology experts.
Requirements for the integrated system involved full DICOM compliance for the exchange of data with different imaging modalities and storage in databases with advanced functions for the display and analysis of radiological images. The encrypted data had to be transferred via e-mail using SMTP and the new DICOM supplement 54. This procedure enables e-mails to be sent through firewalls without any changes in their rule-sets and to make available standard encryption methods for e-mail. The system also had to support autorouting and the automatic protocol conversion between DICOM and SMTP.
Most of this requested functionality was already available in the existing CHILI software, as stated by Dr. Uwe Engelmann from Steinbeis in a paper presentation at the recent Computer Assisted Radiology and Surgery (CARS 2002) Congress. The Steinbeis solution works as follows. The referring hospitals in Neustandt and Worms are equipped with one or more CHILI workstations consisting of a series of PCs running Linux. One workstation is acting as a CHILI server whereas the other ones are CHILI clients.
In the paper, Dr. Engelmann and his team explain how the server receives the images from the imaging modalities, PACS or a DICOM workstation via the DICOM protocol. The server stores the data in a relational database. The CHILI clients are connected to this database in order to view and process the stored data. Teleconferences can be held between all CHILI workstations. Medical staff from the referring hospitals can transmit the data through e-mail using SMTP to the expert centres in Ludwigshafen and Mannheim.
The e-mail messages have to be encrypted since confidential patient data has been integrated into the DICOM images. The Steinbeis solution uses MIME Security with OpenPGP to encrypt and sign the data with the private key of the submitting person. In turn, the receiver applies a public key to decrypt the data. Because the referring hospitals are transmitting large amounts of data, the data automatically is split into different e-mails of a more modest size.
The Steinbeis project team describes how the submission process can be activated either by a user or automatically by a so-called autorouter. In the automatic mode, the submitted data cannot be signed by a person. Therefore, the team uses a private key adhering to the workstation or institution to create a signature to protect the authenticity and integrity of the data. Transmission begins at the point where the DICOM data has been converted into a set of encrypted e-mails. The CHILI server of the referring hospital sends the data out to the external network over an optional firewall. The SMTP port of the firewall is usually accessible for data exchange.
At the expert centre's receiver site, the communication server temporarily stores the incoming data. Usually, this server is located outside the hospital's Local Area Network (LAN) in front of a firewall. The teleradiology servers inside the expert centres behind the firewall fetch the data periodically via the Internet Message Access Protocol (IMAP) from the communication server. The data is decrypted and re-converted into standard DICOM files, stored in the database of the local CHILI server, and made available to the medical staff at the expert centre whenever requested.
Dr. Engelmann and his colleagues note that consultation replies are sent as encrypted e-mails as well to the communication server in front of the firewall. The CHILI server of the referring hospitals is able to fetch the answer and to integrate the report into the local database where it is stored and viewed with the related series of the image data. During each stage of the transmission process, the data transfer is being checked via a secure logging procedure to perform a strict control in terms of accuracy and completeness.
The Steinbeis team in the paper stresses that the CHILI system is not only a dedicated emergency tool but can also be used as a radiological workstation for reporting in daily routine. It is possible to perform interactive in-house teleconferences without sending any data to a remote workstation. Other options, such as long term archiving, image distribution over the intranet, mobile clients, or the use of 3D visualisation modules can be integrated into the emergency system easily.
The pilot project teleradiology for the stroke unit in Rhineland-Palatinate is funded by the Ministry for Employment, Social and Family Welfare, and Health Care in Mainz, Germany. Additional information on the CHILI teleradiology workstation is available in the VMW January 2002 article Mobile CHILI tele-radiology system receives one of 20 IST Prize 2002 awards in Düsseldorf. For more details on the stroke unit pilot project, please visit the CHILI Web site.