DICOM approval sets stage for vendor connectivity

Call it a small step for vendor democracy and a giant leap tosystems connectivity for medical imaging users. Members of theNational Electrical Manufacturers Association's MedPACS sectionlast month voted on and approved the major portion of ACR-NEMA'sdigital imaging and communications in medicine (DICOM) version3.0 standard.

The move paves the way for commercial introduction of DICOM,although much work remains before users will realize the dreamof full vendor connectivity. Ultimately, implementation of theDICOM standard will allow imaging customers to pick and choosetheir scanners without sacrificing flexibility when building picturearchiving and communications systems.

DICOM version 3.0 was unveiled at the infoRAD exhibit at lastyear's Radiological Society of North America meeting (SCAN 12/30/92).The standard, which supports direct network-based connectivityof imaging equipment, is a vast improvement on version 2.0, whichrelies on a 50-pin interface for point-to-point communication.

While version 2.0 was never adopted on a wide scale, version3.0 is sure to have broader appeal. The PACS market has been desperatefor a connectivity standard. In ultrasound, for example, manyvendors have adopted an interim standard, the data exchange fileformat (DEFF), to enable disk-based connectivity between scannersand peripheral devices until DICOM is available (SCAN 9/8/93).

The MedPACS action gives vendors the green light to begin writingDICOM specifications into their devices. It also gives equipmentbuyers who are concerned about connectivity much more guidancewhen shopping for devices from different manufacturers.

Vendors who claim their devices support DICOM must submit conformancestatements detailing the parts of the standard their devices adhereto, according to Dr. Steven Horii, co-chair of the ACR-NEMA committee.

"Companies can't just say, `We conform to DICOM.' Theymust also have a conformance claim that says how they do that,"Horii said. "If you find that two vendors have conformancestandards that say the same thing, it's highly probable that thosetwo implementations will talk to each other."

But DICOM version 3.0 will not completely solve the connectivityimpasse, at least not right away. Within DICOM are three differentcommunications standards--TCP/IP, OSI and the 50-pin connector--andwork remains to be done by vendors in developing their individualDICOM implementations, according to Wayne DeJarnette, presidentof DeJarnette Research Systems.

"The DICOM standard is necessary before you can have inter-manufacturercommunication, but there is still a lot of hard work to be done,"DeJarnette said. "For anybody that went out today and boughtCompany A's DICOM and Company B's DICOM, the chances of thosemerging seamlessly are small."

DeJarnette Research Systems is one of at least six companiesthat will be displaying DICOM implementation software at infoRAD.All versions are based on software developed by the MallinckrodtInstitute for displaying DICOM at infoRAD, and all six implementationswere able to communicate with each other at a trial run of DICOMin September, Horii said.

Work is still being conducted on three sections of DICOM thatwere added to the standard late last year. The sections, parts10, 11 and 12, deal with file formats and were added in part asa response to DEFF.

Of the 21 vendors in the MedPACS section, 18 voted to approvethe standard, one abstained and two did not vote, according toHorii. The standard also won approval from the American Collegeof Radiology's board of chancellors.

The near-unanimity of the vote paralleled the commitment vendorshave made to supporting the standard by dedicating engineers towork on DICOM, Horii said.

"The companies have been really good about supportingtheir people for this," Horii said. "That's part ofthe reason it was successful."

Vendors must exercise caution in the wake of their victory,however. Aggressively pushing DICOM as a panacea for PACS connectivityproblems could end up confusing a market already mystified byPACS.

"There were a number of companies out there that couldn'tspell DICOM a little while ago, and now they are really pushingDICOM," DeJarnette said. "If we oversell this, the industryis going to disappoint customers and in the long term we may endup killing something that was really useful."