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									How to Develop a Supplement
to the

DICOM Standard
Detailed Procedures

Objective The purpose of this document is to provide guidance for individuals and working groups that seek to add significant new capability to the DICOM Standard. The document addresses the following topics: I. II. III. IV. V. VI. VII. VIII. IX. X. XI. Assessing the Need Finding a Home Identifying a Champion and Cohorts Obtaining Authorization to Start Work Efforts within the Working Group Interacting with Working Group Six Preparing for Public Comment Obtaining and Responding to Public Comments Assignment of Codes The “Letter Ballot” Process Responding to Comments

With updates typically occurring every two to three months, the DICOM Standard is one of the most rapidly evolving standards in the world. Nevertheless, it will take a dedicated effort over a period of several months to effect a change in the Standard. The shortest possible time for developing and securing final approval of a supplement is about nine months. At the other extreme, one rather complicated supplement required:
           Three-and-one-half years of working time, 19 face-to-face meetings (12 in Europe and seven in the USA), 13 teleconferences, 24 different participants, Six invited guests, Two editors, 49 versions of the supplement, Five NEMA and four NNI / NEN secretaries, Two chairmen, More than 3000 e-mails and A multitude of Euros for travel expenses.

Comments and/or questions regarding the process may be directed to the DICOM Secretariat. (Visit http://medical.nema.org/dicom/dicomwgs.htm to determine the name and contact information for the current secretary.) However, for overall efficiency, you are encouraged to, first, consult the DICOM Standards Committee’s official Procedures that may be found at:

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http://medical.nema.org/Dicom/Geninfo/Procedur/Procedures_2002-06-25.htm.

I.

Assessing the Need

From time to time, new medical imaging capability enters the market place. Because different vendors independently developed that capability, several different implementation approaches may be offered. To assure interoperability of all equipment offering this new capability, the DICOM Standard must be extended through the addition of a new supplement. Each Supplement affects one or more existing Parts of the Standard, and may even introduce a new part. II. Finding a Home

Members of the DICOM Standards Committee (DSC) and its many working groups are particularly sensitive to identifying the kinds of needs mentioned above. They routinely bring these situations to the attention of the appropriate working group. If none is obvious, then, the information is forwarded to Working Group 10 (Strategy). Members of WG-10 will provide advice regarding the appropriate group to address the need, or they may recommend that the DSC initiate a new group. III. Identifying a Champion and Cohorts

Two things are required to successfully prepare a new supplement to the DICOM Standard – a champion and other interested parties. One cannot simply turn over a suggestion to the appropriate group and wait for its members to do the job. The champion for this cause must be willing to step forward and lead the effort to develop appropriate language for inclusion in the standard. The champion should be or become a member of the designated working group and would usually serve as editor of the supplement while it is being developed. Additionally, there must be participation in the effort by representatives of other organizations that have a material interest in the outcome of this effort. The DICOM Standard will not be extended to cover the products of a single vendor. IV. Obtaining Authorization to Start Work

After obtaining an expression of interest from an existing working group or encouragement from WG-10, the champion needs to prepare a work item request for submission to the DICOM Standards Committee. This should be carefully reviewed and endorsed by an existing working group, which is willing to host the effort, or by WG-10. To see a template for work item requests, please visit:
ftp://d9-workgrps:goimagego@medical.nema.org/MEDICAL/Private/Dicom/WORKGRPS/Committee/Supplement-How_to_Prepare/Templates/Work_Item_Request.doc.

Particular care should be given to estimating the amount of time required of WG-06 in reviewing and approving the supplement as it moves from an early draft to final text. Information regarding these details may be found in Sections VI through XI of this document. After the work item request has been completed and reviewed, the working group should forward it to the DICOM Secretariat. (Visit http://medical.nema.org/dicom/dicomwgs.htm to determine the name and contact information for the current secretary.) The secretary will place it

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on the agenda for the next meeting of the DICOM Standards Committee. After consideration of such factors as state of technology, needs of the user community and workload of both the host working group and Working Group Six, the Committee may authorize development of the new supplement. V. Efforts within the Working Group

Once the work has been authorized, the champion/editor prepares a first draft of the supplement’s outline for discussion with other members of the working group either at a regularly scheduled meeting of the group or during a conference call organized for that specific purpose. Achieving consensus on what is to be included is a critical first step. (The group’s secretary will arrange the meetings or conference call and prepare the minutes.) Work proceeds in an iterative process from meeting to meeting. Detailed language (normative and informative) is developed and added to the outline. As work progresses, the editor must be careful to assure that:    The Standard remains backward compatible – i.e., nothing can be included in the new supplement that will conflict with existing stipulations of the Standard. There is no duplication of existing parts of the standard; however, such material may be referenced. Each addition to the standard addresses aspects of interoperability of equipment by defining protocols for communication and information exchange – not through functional specifications for such equipment. Existing features of the standard (attribute tags, names and definitions, coded terminology, information object definitions, service definitions and communication protocol definitions are utilized as much as possible).



Editors must assure that each new supplement is formatted in accordance with the supplement template provided at:
ftp://d9-workgrps:goimagego@medical.nema.org/MEDICAL/Private/Dicom/WORKGRPS/Committee/Supplement-How_to_Prepare/Templates/Supplement_02.DOT.

A working group may have difficulty defining the structure of a new supplement and its potential content – e.g., when no similar features are already present in the standard. In that case, the champion may wish to prepare and present a white paper discussing those challenges to Working Group Six as described in Section VI below. VI. Interacting with Working Group Six

Preview Meeting Once the group has agreed on the outline of the supplement and begun to add some text, or when the review of a white paper on a subject is necessary, the editor or the group's chair should contact the chair and secretary of WG-06 (Base Standard) to schedule a preliminary review of the document. For the name and address of these individuals, see:
http://medical.nema.org/dicom/dicomwgs.htm.

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This preview meeting serves as a “proof of concept” and requires the editor’s presence for about one hour during a regular meeting of WG-06 (usually at NEMA’s Headquarters in the Washington, DC area). The draft document should be posted in the “Supplements” folder on the WG-06 private ftp site at least two weeks prior to the meeting date. (Individuals who are not familiar with the process of posting documents to ftp servers may contact the Committee’s secretariat for assistance.) At the time it is first posted, the document should be identified as “wgYY_title.doc” where “YY” is the number of the working group (with a leading 0 if necessary) and “title” is a short title indicative of the content. Members of WG-06 have extensive and detailed knowledge of the entire Standard and can be extremely helpful in:    Guiding the editor of a supplement around common pitfalls, Assuring that various parts of the Standard do not conflict with one another and Solving problems that others have faced in previous efforts to amend the standard.

At this first meeting with WG-06, the editor, who may be accompanied by other members of the working group, provides an overview of the document and collects recommendations from WG06. If the document is sufficiently mature, it will be assigned a supplement number and listed in the Supplement Log at:
ftp://medical.nema.org/medical/dicom/Supps/.

If the document is not yet formatted as a supplement draft, it will be designated with a status of Preliminary, otherwise, it will be designated as Early Draft. With this number in hand and lots of advice from WG-06, the editor and working group continue to develop and refine their document. Following this Preview Meeting, the document should be named: “supnn_xx.doc” where “nn” is the two-digit number of the supplement (with a leading 0 if necessary) and “xx” is the two-digit version number of the document (with a leading 0 if necessary). First Reading When the draft supplement is fairly complete and has been approved by members of the responsible working group, the editor or group chair should notify the chair and secretary of WG-06 that he or she is ready to present the document for a first reading. This will require his or her presence for at least two two-hour sessions (separated by one night) during a regular meeting of WG-06. Of course, other members of the working group may accompany the editor at this meeting. The document should be posted in the “Supplements” folder on the WG-06 private ftp site at least two weeks prior to the meeting date where the First Reading will occur. It needs to be formatted according to the structure and styles as described in the template that may be found at:
ftp://d9-workgrps:goimagego@medical.nema.org/MEDICAL/Private/Dicom/WORKGRPS/Committee/Supplement-How_to_Prepare/Templates/Supplement_02.DOT.

To assure proper maintenance of the standard, it is very important to follow the standardized styles and not to introduce new ones. The First Reading by WG-06 is generally a three-stage event:

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  

Members of WG-06 listen to a presentation on the first day and provide some guidance on how to improve the draft supplement. The editor, then, retires to his or her hotel and makes the recommended changes. He or she posts the revised document on the ftp site for downloading and additional review on the second day. On the second day, members of WG-06 review the revised document to see how their suggestions have been incorporated and, also, to ensure that the recommended changes did not introduce new problems.

Depending on the scope and complexity of the supplement under development, this review and iteration with WG-06 may need to be repeated one or more times. Be aware that WG-06 has only limited bandwidth. Try to maximize the exposure of all issues and problems during the review meetings. VII. Preparing for Public Comment

Public Comment period is an important part of the Supplement development work. It allows the champion and other developers of the supplement to verify their approaches and request opinions of vendors and users on the wide variety of issues. Members of the group developing the supplement, now, work toward the goal of creating the public comment version of the supplement. (This usually involves a few conference calls with the group's members -sometimes enhanced with "WebEx" so that all participants can see the document on their computer screen as the editor modifies it. The working group’s secretary can arrange the conference calls and WebEx capability.) Depending on the scope and complexity of the supplement, the working group may need to request assistance from WG-6 to verify the many decisions that will have to be made along the way. VIII. Obtaining and Responding to Public Comments When the working group developing the document determines that the supplement is ready, or almost ready, to be released for public comment, the document’s editor or the group's chair contacts both the chair and secretary of WG-06 to request time on the agenda of its next meeting. Usually, about nine hours on the WG-06 agenda are reserved for this discussion (three hours per day for three days with sleepless nights devoted to making revisions). The editor, who may be accompanied by one or more members of the working group, participates with WG-06 in a lineby-line review of the document with the aim of getting it in shape for public comment. (For complex supplements, several meetings may be required before the document is approved for release to obtain public comments.) Finally, the editor will be authorized to complete any last minute revisions and seek public comments on the draft supplement. Once the final revisions from WG-06 have been incorporated in the document, it is given a new name “supnn_pc.doc” and forwarded to the DICOM Secretariat for distribution to the entire DICOM community. Additionally, members of the working group sponsoring the document are encouraged to provide the names and e-mail addresses of individuals outside the DICOM community who have sufficient knowledge of the subject area to provide useful evaluation of its contents.

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The DICOM secretary will forward the draft supplement to the DICOM community and all additional named reviewers. Each will be given 45 days to prepare and return comments on the draft. These comments will be collected by the secretary and forwarded to the sponsoring working group. Members of the sponsoring working group, then, need to consider each comment and make such revisions as they consider appropriate. While the public comment process is underway, the editor or group chair must determine whether the new supplement will use concept codes and controlled terminology such as SNOMED, LOINC or the DICOM Content Mapping Resource (DCMR).  If codes need to be assigned, the editor should request time on the agenda of WG-08 (Structured Reporting), which maintains the DCMR and serves as a liaison to other controlled-terminology resources. See item IX below. The goal, here, is to obtain proper resolution on the code assignment during the public comment process. If codes are not required, then, when all comments have been addressed, the editor, again, requests time on the agenda of WG-06. See item X below. Assignment of Codes



IX.

If codes need to be assigned, the document must be presented to Working Group Eight. This may involve a personal presentation to the members of WG-08 at one of its regular meetings. If the codes to be used within the supplement will come from a non-DICOM source, it may take a while for WG-08 to work out necessary details with the corresponding controlled-terminology body. Still, it is imperative that this work be undertaken as part of the public-comment resolution process. Once the public comments have been addressed and the required codes have been assigned, the editor needs to bring the document, again, to WG-06 for review. X. The “Letter Ballot” Process

The editor brings the revised document – together with an account of how the comments were addressed – to WG-06 for another line-by-line review. As before, the revised document should be placed in the “Supplement” folder on the WG-06 ftp site at least two weeks in advance of the WG-06 meeting. At this point it should be labeled “supnn_pc+1.doc.” The goal, at this point, is to achieve a draft worthy of presentation to the DICOM Standards Committee for ballot. This is, potentially, one of the most painful procedures since the document is reviewed line-by-line and verified for any inconsistencies with the existing standard and other supplements in progress. Again, it may take more than one meeting to achieve consensus on Letter-Ballot text. Due to the intense nature of this review, the editor should plan to spend at least two hours per day for each of three days with WG-06. Depending on the complexity of the supplement as well as the number and nature of comments received, this process may need to be repeated. When WG-06 finally gives its approval, the document is prepared for letter ballot. Two versions need to be prepared – one in Microsoft Word and another in Portable Document Format. It is, now, labeled “supnn_lb.doc” and “supnn_lb.pdf” and sent to the DICOM Secretariat. After review by NEMA’s legal counsel, the secretary forwards it to Committee members for vote. Each member is allowed 49 days to cast its ballot. Members have four possible options:

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    XI.

Approve, Approve with comments, Disapprove with comments and Abstain. Responding to Comments

Following the letter ballot, the secretariat reports the results to WG-06 and sends any ballot comments to the working group that is responsible for the supplement. It is the responsibility of the parent group to address all ballot comments and suggest final text to WG-06. WG-06 considers all comments from the letter ballot according to the secretariat's procedures. It may direct the editor to prepare a final proposed standard (Final Text) and an explanation of how each comment was resolved. These are submitted to the secretariat and officers of the Committee. If the secretariat and either co-chair determine that all comments received during the letter ballot have been addressed according to the DICOM Standards Committee’s official Procedures and if there are no technical differences that directly and materially affect the use of the standard between the Letter-Ballot Text and the Final Text, then, the supplement is approved for inclusion in the standard. When the final text has been approved, the editor places both a “.pdf” and a “.doc” version of the document on the ftp site at:
ftp://d9-workgrps:goimagego@medical.nema.org/MEDICAL/Private/Dicom/WORKGRPS/Incoming/ .

However, if the secretariat and either co-chair determine that there are minor technical differences between the Letter-Ballot Text and the Final Text, the secretariat must inform all members of the Committee regarding the nature of the changes. Each member must be given a 30-day opportunity to change its vote. At the conclusion of this period, the secretary recounts the votes and determines whether, in view of these changes, the standard is approved or rejected. If the secretariat and either co-chair determine that there are major technical differences between the Letter-Ballot Text and the Final Text, another ballot will be required.

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