CORBA may be cure for DICOM deficiencies

October 8, 2001

DICOM (digital imaging and communications in medicine) is the industry standard for moving digital images between computers. Some experts warn that DICOM alone, however, is insufficient for enabling highly scalable interoperability between networks that

DICOM (digital imaging and communications in medicine) is the industry standard for moving digital images between computers. Some experts warn that DICOM alone, however, is insufficient for enabling highly scalable interoperability between networks that are growing more heterogeneous, diverse, and geographically distributed.

One alternative for linking complex software systems is distributed object computing using a protocol called CORBA (common object request broker architecture).

"DICOM requires that clients (digital imagers) and servers (storage servers) know of each other prior to making connections," said Andrew Van Nguyen, a computer scientist in electrical and computer engineering at the University of California, San Diego.

In other words, the storage server's IP (Internet protocol) address is given to the client before the client can make any requests. Each client has a list of servers and queries, each one asking, "Can you store this type of image?" After receiving a response, the client then proceeds with the transaction.

"The problem with the DICOM model is we have many single points of failure," Nguyen said. "If one of the storage servers goes down, a technician would have to bring up another server with the same IP address or change the client to point to another server."

Under CORBA, however, all objects are available over the network, so the clients, servers, and coordinators are all accessible by each other.

"Not only does this simplify the process, it also protects us from single points of failure," Nguyen said. "It is possible to recognize multiple coordinators on the network, and if one fails the others would continue the work."

The same can be done with the servers. Redundancy is automatic without the need for technicians to manually reconfigure various machines when there is partial failure of the network.

Other experts applauded any effort that encourages the modernization of DICOM.

"The reporting of positive experiences, and other help from the customer and IT communities, can encourage and perhaps spur DICOM toward modernizing its syntax and transport layers," said Doug Sluis, Ph.D., a DICOM-ultrasound expert at Philips Medical Systems. "Modernization is a controversial subject in the DICOM community."

Changing protocols, which requires serious effort within the DICOM technical working groups, means an awkward transition period during the move from one protocol to another, so a conservative stance by DICOM is justified, he said.

"I agree that CORBA is functionally equivalent and in some ways superior to the DICOM, but I believe that W3C (World Wide Web Consortium) standards, specifically XML (extensible markup language) will gain far more acceptance and overtake CORBA," he said.

The benefits of being able to leverage newer technologies like CORBA and XML can overcome their short-term costs, however.

"These technologies can significantly expand capabilities, by overcoming the awkward and limited query functionality in DICOM," Sluis said.