1. Review of WG17 Work Item 1 Output: DICOM Encapsulated STL
Allan Noordvyk & Justin Ryan
Co-Chairs of WG17: 3D Manufacturing

2. Working Group 17 3D Manufacturing
Agenda
WG17 Mandate & Work Item
Specifics of Proposal
New IOD / SOP
Other related changes
Expected use by community
Strategy for adoption by vendors
Larger WG17 context & future
Open Questions
Working Group 17 3D Manufacturing

3. Working Group 17 3D Manufacturing
WG17 & Work Item
Our mandate is to facilitate a way to store/query/retrieve 3D models, intended for 3D manufacturing, as DICOM objects (Work Item 1). The approved Work Item is focused on (a) leveraging the existing and growing ecosystem of DICOM-capable systems in use in healthcare institutions and (b) leveraging standards already in use in the 3D printing industry.
Working Group 17 3D Manufacturing

4. Working Group 17 3D Manufacturing
Specifics of Proposal
New Information Object Definition (IOD):
Encapsulated native 3D file for Creation, Review, Update, and Printing (manufacturing)
New Service Object Pair (SOP):
Encapsulated STL Storage
Working Group 17 3D Manufacturing

5. Specifics of Proposal (cont’d)
Other extensions to DICOM standard
Contain references to existing IODs from which the model is derived (which may be from multiple studies)
Allow users to review 3D printing models for accuracy/relevance prior to printing
Include a 2D preview representation
Indicate whether the 3D printed model contains protected health information
Working Group 17 3D Manufacturing

6. Working Group 17 3D Manufacturing
Expected Use
The new IOD/SOP is expected to address these real world use cases:
Creation
Review
Update
Print
Working Group 17 3D Manufacturing

7. Expected Use (continued)
Use Case 1: Creation
Medical reconstruction software queries Image manger system
User creates patient-specific 3D model (reconstruction and modeling)
Modeler system creates the new type DICOM object containing the 3D model, populating all required metadata
User saves 3D model back to the patient’s record in DICOM format as either (a) an addition to an existing study or (b) a new study
The Modeler system stores the new DICOM object in the Image Manager system
PACS/VNA
PACS/VNA
Working Group 17 3D Manufacturing

8. Expected Use (continued)
Use Case 2: Review
At a later time to Use Case 1, a user indicates desire to visually review a 3D model , prior to 3D printing
The Display system queries the Image Manager for the DICOM objects of new type
The Display system retrieves the indicated object
The Display system extracts the 3D model from the object and displays it to the user, potentially registered for simultaneous display with source images
PACS/VNA
Display System
Working Group 17 3D Manufacturing

9. Expected Use (continued)
Use Case 3: Update
At a later time to Use Case 1, a user indicates desire to modify a 3D model for a particular patient
The Modeler system queries the Image Manager for the DICOM objects of new type
If necessary, the Modeler system retrieves any source images (s1 to sN) required for this modification to occur
User interacts with the Modeler system to adjust the 3D printable model as desired
PACS/VNA
Working Group 17 3D Manufacturing

10. Expected Use (continued)
Use Case 3: Update (cont’d)
User saves back to the patient’s record in DICOM format as either (a) an addition to an existing study, or (b) a new study
The Modeler system creates the new type DICOM object containing the new version 3D model, populating all required metadata and including a unique identifier reference to the supplanted earlier 3D print model object
The Modeler system stores the new DICOM object in the Image Manager system
PACS/VNA
Working Group 17 3D Manufacturing

11. Expected Use (continued)
Use Case 4: Print
At a later time to Use Case 1, a user indicates desire to print a 3D model for a particular patient
The Print Manager system queries the Image Manager for the DICOM objects of new type belonging to the patient
The Print Manager system retrieves the indicated 3D print model object
The Print Manager access the 3D model information within the object, using this to create non-DICOM print instructions for a specific 3d printer (e.g. .stl)
PACS/VNA
Print Manager
Working Group 17 3D Manufacturing

12. Expected Use (continued)
Use Case 4: Print (cont’d)
The Print Manager prompts the user for any necessary additional print parameters (e.g. support, bed placement, material parameters, etc.)
The Print Manager submits the print job to the printer
Optionally, the Print Manager may save an updated 3d print object back to the Image Manager in order to preserve exact print parameters used (per Use Case 3, steps 7+).
Print Manager
PACS/VNA
Working Group 17 3D Manufacturing

13. Working Group 17 3D Manufacturing
New Module
Introduces Module: Manufacturing 3D Model
Addresses 3D model (3DM) information not present in either current DICOM or STL model data formats
Contains 3 attributes:
Measurement Units Code Sequence
Model Modification
Model Mirroring
Model Usage
We expect this module will be used in future additional 3D manufacturing related IODs
Working Group 17 3D Manufacturing

14. Working Group 17 3D Manufacturing
New Module Attribute 1
Measurement Units Code Sequence
Specifies how the unit scale of the STL file should be interpreted
Removes ambiguity
Allowed Values: m cm mm um
Working Group 17 3D Manufacturing

15. Working Group 17 3D Manufacturing
New Module Attribute 2
Model Modification
Specifies whether modification (beyond mirroring) was used to create the model
Specifies whether the object represents the observed patient anatomy in the source data
Enumerated Values:
Yes No
Working Group 17 3D Manufacturing

16. Working Group 17 3D Manufacturing
New Module Attribute 2
Model Mirroring
Specifies whether mirroring of anatomy from the other side of the patient was used to create the model
Enumerated Values:
Yes No
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17. Working Group 17 3D Manufacturing
New Module Attribute 3
Model Usage
Specifies the use for which the manufactured object is initially intended.
Defined Terms:
Education
Diagnosis/Planning
Instrument
Prosthetic/Orthotic
Implant
Quality Control
Simulation
Working Group 17 3D Manufacturing

18. New Module Attribute 3: Terms
Model Usage: Defined Terms
EDUCATION Modeled object is intended for patient or care-giver education / informed consent, or training residents and fellows
DIAGNOSIS/PLANNING Modeled object is intended to be used to assist with diagnosis and/or pre-operative procedure planning
INSTRUMENT Modeled object is intended to be used as a patient-matched intra-operative tool during a medical procedure
PROSTHETIC/ORTHOTIC Modeled object is intended to be used as a fully external prosthetic/orthotic
IMPLANT Modeled object is intended to be used as a wholly or partially internal implant
QUALITY CONTROL Modeled object is intended to be used for quality control purposes
SIMULATION Modeled object is intended to be used for simulation and/or practice of a surgery or other medical procedure.
Working Group 17 3D Manufacturing

19. Other Aspects Addressed
Patient Confidentiality
Clarified use of existing Burned in Annotation and Recognizable Visual Features attributes as they apply to 3D models
Preview Image
Desired to allow for visual selection of different models in same study without need to load, interpret and render
Pre-rendered image optionally supplied when IOD created
Leveraged existing method - (0088, 0200) Icon Image Sequence – to illustrate pre-rendered preview image
Working Group 17 3D Manufacturing

20. Working Group 17 3D Manufacturing
Strategy for Adoption
Success depends on both:
Traditional PACS/VNA vendors, and
3D print model software vendors
Both must adopt the new standard simultaneously
Working Group 17 3D Manufacturing

21. Strategy for Adoption (cont’d)
Groundwork for success is as follows
Enable traditional PACS/VNA vendors and new 3D print model software vendors to participate in new IOD development
Enable user community to push their vendors to adopt the new IOD via:
User group meetings
Conferences
Society meetings (RSNA, SME, WAM3DP, etc.)
Working Group 17 3D Manufacturing

22. Working Group 17 3D Manufacturing
Larger WG17 Context
Work Item requires us to support more than just STL:
STL captures geometry as a triangular mesh, but contains no metadata (e.g. units) or color
G-CODE, VRML/X3D, AMF, 3MF, PLY, OBJ/MTL, VTK, FBX and U3D/PDF
Some have prohibitive licensing
Future Encapsulation Prospects
Ballot ended for next proposals: OBJ/MTL, VRML/X3D, and 3MF
contain metadata, color information, enhanced geometrical representations
Working Group 17 3D Manufacturing

23. Working Group 17 3D Manufacturing
Open Question #5
Would inclusion of selected attributes of the implant description module be beneficial for 3D models that are intended to be implants?
Working Group 17 3D Manufacturing

24. Working Group 17 3D Manufacturing
Open Question #6
Would there be meaningful benefit from incorporating further implant detail via the use implant defined terms, code sets, or other encoding (e.g. CID 73xx family)?
Authors left out such level of detail in the interest of simplicity. However, a hip assembly can contain 20 parts. It is possible that it would be useful to identify which part is represented by which model. However, existing means of identification (e.g. Document Title) may be sufficient for real-world use.
Working Group 17 3D Manufacturing

25. Working Group 17 3D Manufacturing
Open Question #7
Is the existing use of Frame-of-Reference adequate to handle registration in all cases?
Authors believe it does. Also, follows current conventions of 3D modeling software (model uses coordinate system of primary source series).
Working Group 17 3D Manufacturing

26. Working Group 17 3D Manufacturing
Open Question #8
The Model Usage attribute does not distinguish between different types of instrument guides. Is there actual value to adding additional granularity (e.g. distinguishing needle, blade, drill guides) sufficient to justify additional complexity?
The additional granularity was initially included, but later omitted by the authors in the interest of simplicity.
Working Group 17 3D Manufacturing

27. Working Group 17 3D Manufacturing
Open Question #9
The Model Usage attribute does not distinguish between different levels of permanence for implants. Is there actual value to adding additional granularity (e.g. distinguishing absorbable, removable, and permanent implants) to justify additional complexity?
The additional granularity was initially included, but later omitted by the authors in the interest of simplicity.
Working Group 17 3D Manufacturing

28. Working Group 17 3D Manufacturing
Open Question #10
The Module Usage attribute is included to help filter when multiple models are returned a query, routing for handling, etc. Are the values selected sufficient for these use cases?
Working Group 17 3D Manufacturing

29. Working Group 17 3D Manufacturing
Open Question #11
Is reference to a small number of representative images sufficient for the goal of supporting linked comparison?
Our options thus appear to be (a) require only a small number of representative images from each source series or (b) define a different attribute that represents a series-level reference.
Working Group 17 3D Manufacturing

30. Working Group 17 3D Manufacturing
Open Question #12
Is using only metric units from um to sufficient for to identify any scale in routine use for medical and non-destructive-testing purposes?
We only used metric units for patient safety reasons and to match current clinical practice (which appears to universally use either mm or m).
We created a new context group specifically for 3D printing scale (7xx3). This ensures that other units could be added in the future should a new use case arise.
Working Group 17 3D Manufacturing

31. Working Group 17 3D Manufacturing
Open Question #13
Related to the question above. Is a multiplication factor for unit scale also required?
For example, there is no way to specify that the unit scale of the model is 2.54 mm. Instead the creator of the STL would need to divide all coordinates in the file by 2.54 and specify the unit scale as mm.
Working Group 17 3D Manufacturing

32. Working Group 17 3D Manufacturing
Open Question #14
What other derivations need to be added to LOINC for 3D print models? Currently only CT and MR derived models can be coded using LOINC references. Also, what is the best way to capture fused multi-modality fusion models in a single LOINC code?
Some individuals are working with 3D printing from ultrasound. We assume it should be added to LOINC.
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33. Working Group 17 3D Manufacturing
End of Presentation
Questions?
Working Group 17 3D Manufacturing