Indian Journal of Radiology and Imaging Indian Journal of Radiology and Imaging

: 2007  |  Volume : 17  |  Issue : 2  |  Page : 66--68

DICOM, HL7 and IHE: A basic primer on Healthcare Standards for Radiologists

IK Indrajit, BS Verma 
 Department of Radiodiagnosis and Imaging, Army Hospital (Research and Referral), Delhi Cantt - 110 010, India

Correspondence Address:
I K Indrajit
Department of Radiodiagnosis and Imaging, Army Hospital (Research and Referral), Delhi Cantt - 110 010

How to cite this article:
Indrajit I K, Verma B S. DICOM, HL7 and IHE: A basic primer on Healthcare Standards for Radiologists.Indian J Radiol Imaging 2007;17:66-68

How to cite this URL:
Indrajit I K, Verma B S. DICOM, HL7 and IHE: A basic primer on Healthcare Standards for Radiologists. Indian J Radiol Imaging [serial online] 2007 [cited 2021 Mar 3 ];17:66-68
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Full Text

 An Introduction to Healthcare Standards

With the widespread use of computers in medicine, it is now possible to have "filmless" radiology department and "paperless" hospitals. To make this happen, radiology modalities using computers should be connected seamlessly and computers in a hospital need to be integrated into a network.

Over the years, certain standards have been formulated for radiology departments, endowed with modalities using digital technology (Ultrasonography, CT, MR etc) and peripheral devices like laser printers. Digital Imaging and Communications in Medicine (DICOM), is one such standard, which deals with imaging equipment, printers, picture archival and communication systems (PACS), etc. It also offers assorted functions such as film printing or CD burning, which are distinctly determined by service classes. A broad knowledge of service classes is important while installing and handling radiology equipments.

On the other hand, in a hospital-based scenario, for managing nonimaging data, Health Level Seven (HL7) as a standard is useful. It provides protocols for exchange, management and integration of clinical and administrative electronic health data. Its area of focus is on clinical interoperability of health records and it interfaces the requirements of the entire healthcare organization.

To a modern day radiologist, three important health care standards and initiatives need to be understood. They include DICOM, HL7 and IHE (Integrating the Healthcare Enterprise). Their salient features are outlined in [Table 1].

1. Digital Imaging and Communications in Medicine (DICOM)

For handling imaging data, DICOM has been developed by the American College of Radiologists (ACR) and National Electrical Manufacturers Association (NEMA). This cooperative standard assists communication between various image based modalities and accessories to each other. [1] Broadly, it focuses on workflow of images. It provides reliable protocols for integration of image data between imaging, nonimaging modalities, devices and systems. The functional elements broadly comprise of Protocols, Objects, Services, Service Class and Conformance. [3]

In particular, DICOM Service Class is defined as a group of operations that a user wants to perform on data from a modality. Typical examples of Service Classes include Print Management Service Class that deals with printing images on film or paper printer, with flexible film formats, Storage Service Class that implies "sending" images and Query/Retrieve Service Class that deals with issues of "find, move and get" SOP (Service Object Pair) Classes. While "find" is used to query for images, "move" and "get" are used to commence a transfer. Other classes of service include Verification Service Class, Media storage, Study content notification, Print management, Patient management, Study management, Result management, Modality Performed Procedure Step management States and Structured reporting.

2. Health Level Seven (HL7)

For managing nonimaging data, HL7 or Health Level Seven provides protocols for exchange, management and integration of clinical and administrative electronic health data. Health Level Seven is "an all-volunteer, not-for-profit" organization. [2] Formed in 1987, it is the accepted global standard for exchange, integration, sharing and retrieval of electronic health information in Hospitals.

The term Health Level "Seven" has its origins based on a seven-layer International Organization of Standards (ISO) Communication Model. Each layer has a role wherein layers one to four deal with communication; comprising Physical, Data Link, Network and Transport communication layers. Layers five to seven deal with functions like Session, Presentation and Application. The highest level or seventh level is regarded as the application level, which deals with the definition of data to be exchanged. [4] This level supports varied functions, such as "security checks, participant identification, availability checks, exchange mechanism negotiations and data exchange structuring". [5]

HL7 allows the "interoperability between electronic patient administration systems, practice management systems, laboratory information systems, dietary, pharmacy and billing systems, as well as electronic medical record (EMR) and electronic health record (EHR) systems". [2] HL7 Standards are freely implementable, but have a strict copyright. [5]

3. Do DICOM and HL7 have all the answers?

It is important to understand that radiology requires more than DICOM for workflow. In radiology departments, intersystem communication transactions are not handled by any one vendor or any one healthcare standard. Existing standards like DICOM and HL7 have been established and are in place. These standards lay down that interoperability is possible.

But in practice, integrating information systems in radiology departments can be complex. When standards like DICOM and HL7 are applied on ground, there are ambiguities and conflicting interpretations. [6] IHE (Integrating the Healthcare Enterprise) steps in to fill a gap between what is theoretically possible and what can be achieved in practice on ground in radiology departments.

IHE solves issues involving "multiple, heterogeneous information systems" by way of consensus and cooperation between existing healthcare standards agencies. [7] It coordinates the use of established standards like DICOM and HL7 but answers issues that remain unresolved within the ambit of DICOM and HL7. [6],[8],[9]

4. Integrating the Healthcare Enterprise (IHE)

The core strategy of "Integrating the Healthcare Enterprise" (IHE) is integrating radiology workflow within a healthcare setup, [10] using existing standards like DICOM and HL7. By a "multi-year initiative that creates the framework for integrating applications, systems and settings across the entire healthcare enterprise" the IHE initiative improves workflow. [11] IHE accomplishes this by a four stage process: a) interoperability problem identification; b) integration profile specification; c) implementation and testing at connectathon and d) integration profile conformance statements. [6]

Each year, IHE organizes "Connectathon"in Asia, Europe and North America, which are the healthcare information technology (IT) industry's largest interoperability testing event with vendor-to-vendor contact. Connectathons offer an open invitation to the vendor community and thousands of cross-vendor tests are performed using advanced testing tools. [12] The results are recorded, published and are available online at IHE Connectathon Results at "> , [13] wherein compatibility data is obtained by selecting any combination of connectathon, vendor, actor or integration profiles.

Radiology uses workflow processes. Its formalization is achieved by IHE using 'Implementation Profiles' that deal with transactions that communicate clinical data. IHE Profiles provide precisely how the healthcare standards can be implemented efficiently. The evolving process is annually time-bound and allows expansion. IHE Profiles "eliminate ambiguities, reducing configuration and interfacing costs and ensuring a higher level of practical interoperability." [11]

Typical examples of a few successfully implemented IHE Integration Profiles [14] in radiology departments include Consistent presentation of images profile which ensures images are displayed as similarly as physically possible on different displays like film on viewbox, workstation, or PC. Key image notes profile which is used for flagging images of radiologic procedures. "Key image" is practically useful, for example in a CT Scan of the abdomen, where out of the nearly 200 slices, useful information may be available in only four images. Flagging of these four images enables referring clinicians across a PACS to quickly access them, thereby saving time and increasing efficiency.

Other IHE Integration Profiles include Scheduled work flow, Patient information integration reconciliation, Post processing workflow, Charge posting, Simple image and numeric reports, Presentation of grouped procedures, Access to radiology information, Exception management work flow, Basic security and Integration profile.

IHE Integration Statements are the final outcome, wherein vendors offer declaration of support for specific products. These describe the conformance of their products with the IHE Technical Framework. For those interested, Vendor Integration Statements in a single index page are available from: "> [15]

 Summary and Conclusion

Radiology is a ubiquitous healthcare service that derives, processes, offers and distributes data in an electronic format. Healthcare standards like DICOM, HL7 and initiatives like IHE have been created to improve workflow efficiency in a networked radiology department, across a multivendor system environment. In times ahead, further evolution of healthcare standards will be determined not only by developments in the computer and breakthroughs in medical/imaging equipments, but will as well be dictated by the emergent needs of the entire healthcare enterprise.


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