Overview: Supplement 205 DICOM Encapsulation of STL Models for 3D Manufacturing. Allan Noordvyk & Justin Ryan Co-Chairs of WG17: 3D Manufacturing

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1 Overview: Supplement 205 DICOM Encapsulation of STL Models for 3D Manufacturing Allan Noordvyk & Justin Ryan Co-Chairs of WG17: 3D Manufacturing

2 Contents Background Main Components Expected Use Specific Changes Working Group 17 3D Manufacturing 2

3 Background Working Group 17 3D Manufacturing 3

4 WG17 Mandate Working Group 17 mandate Allow store/query/retrieve 3D models, intended for 3D manufacturing, as DICOM objects Addressed by Work Item 1 Leverage a) Existing and growing ecosystem of DICOMcapable systems in use in healthcare institutions and b) Standards and conventions already in use in the 3D printing industry Working Group 17 3D Manufacturing 4

5 Format Challenge ISSUE: There are numerous standardsbased file formats in current use within the medical 3D printing community The working group decided to initially focus on the most ubiquitous, simplest format: STL We expect to address other formats with their unique capabilities in future Working Group 17 3D Manufacturing 5

6 Main Components of Supplement Working Group 17 3D Manufacturing 6

7 This Supplement The first output of work item 1 is Supplement 205: DICOM Encapsulation of STL Models for 3D Manufacturing Adapts encapsulation approach used for other documents Working Group 17 3D Manufacturing 7

8 New Object / SOP New Information Object Definition (IOD): Encapsulated native STL file for Creation, Review, Update, and Printing (manufacturing) New Service Object Pair (SOP): Encapsulated STL Storage Working Group 17 3D Manufacturing 8

9 New Module New Manufacturing 3D Model Module Addresses medical 3D model information not present in either current DICOM or STL model data formats Contains a mix of newly defined and preexisting attributes not present in Encapsulated Document module We expect this module will be used in future additional 3D manufacturing related IODs Working Group 17 3D Manufacturing 9

10 Expected Use Working Group 17 3D Manufacturing 10

11 Expected Use The new IOD/SOP is expected to address these real world use cases: Creation Review Update Print Working Group 17 3D Manufacturing 11

12 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 12

13 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 PACS/VNA Display System 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 Working Group 17 3D Manufacturing 13

14 Expected Use (continued) Use Case 3: Update PACS/VNA 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 Working Group 17 3D Manufacturing 14

15 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 15

16 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 PACS/VNA Print Manager 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) Working Group 17 3D Manufacturing 16

17 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.) Print Manager 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+). PACS/VNA Working Group 17 3D Manufacturing 17

18 Specific Changes to Standard Working Group 17 3D Manufacturing 18

19 Payload Builds on approach used for encapsulation other file formats (PDF, CDA) STL file encoded via Encapsulated Document (0042,0011) attribute Registration of new MIME type model/vnd.stl pending with IANA More compact binary variant only supported no ASCII Working Group 17 3D Manufacturing 19

20 Source Images Reference References to images from which the model is derived (if known) Allows users to review models vs. patient anatomy for accuracy/relevance prior to printing Addressed through Source Instance (0042,0013) attribute With frame of reference / registration addressed per standard Working Group 17 3D Manufacturing 20

21 Predecessor Instances Optionally reference objects representing prior models, on which new model is based Including classifying nature of the changes Supports workflows around successive refinement editing Uses Predecessor Documents Sequence (0040,A360) attribute Working Group 17 3D Manufacturing 21

22 PHI Management 3D printing introduces some new wrinkles to protecting patient s privacy Clarified use of existing attributes when applied to 3D models Burned In Annotation (0028,0301) Recognizable Visual Features (0028,0302) Working Group 17 3D Manufacturing 22

23 Disambiguated Scale ISSUE: STL files have no inherent scale Relying on humans to guess scale the creator intended is a patient safety issue Addressed via Mandatory Measurement Units Code Sequence (0040,08EA) used to specify at time of creation Uses codes from new Model Scale Units CID Allowed Values: m cm mm um In New Manufacturing 3D Model Module Working Group 17 3D Manufacturing 23

24 Modified Anatomy Indication ISSUE: Some models represent patient current anatomy, while others project results of interventions Risk of confusion New Attribute: Model Modification Enumerated Values: Yes No Specifies whether modification (beyond mirroring) was used to create the model Specifies whether the object represents the observed patient anatomy in the source data Optional since may not always be known In New Manufacturing 3D Model Module Working Group 17 3D Manufacturing 24

25 Mirroring Indication ISSUE: Some models leverage bilateral symmetry to simulate absent or damaged anatomy Risk of confusion New Attribute: Model Mirroring Specifies whether mirroring of anatomy from the other side of the patient was used to create the model Optional since may not always be known Enumerated Values: Yes No In New Manufacturing 3D Model Module Working Group 17 3D Manufacturing 25

26 Model Usage ISSUE: The intended use of a model may not always be clear from appearance Risk of confusion New Attribute: Model Usage Specifies the use for which the manufactured object is initially intended using new CID Defined Terms: Education Diagnosis/Planning Instrument Prosthetic/Orthotic Implant Quality Control Simulation In New Manufacturing 3D Model Module Working Group 17 3D Manufacturing 26

27 Model Usage Values EDUCATION DIAGNOSIS PLANNING INSTRUMENT PROSTHETIC IMPLANT QUALITY CONTROL SIMULATION The modeled object is intended for patient or care-giver education/informed consent, or training residents and fellows. The modeled object is intended to be used to assist with diagnosis. The modeled object is intended to be used to assist with preoperative procedure planning. The modeled object is intended to be used as a patientmatched intra-operative tool during a medical procedure. Modeled object is intended to be used as a fully external prosthetic/orthotic Modeled object is intended to be used as a wholly or partially internal implant Modeled object is intended to be used for quality control purposes Modeled object is intended to be used for simulation and/or practice of a surgery or other medical procedure. Working Group 17 3D Manufacturing 27

28 Preview Image ISSUE: Visual selection helpful when multiple different models in same study Optionally include 2D preview image representation Avoids need to load, parse, and render the model just for a quick preview Uses Icon Image Sequence (0088,0200) Working Group 17 3D Manufacturing 28

29 Derivation Algorithm ISSUE: Users may wish to known which modeling software algorithm was used to produce a particular model Optionally record the algorithm used to perform the derivation Uses Derivation Algorithm Sequence (0022,1612) attribute Working Group 17 3D Manufacturing 29