DICOM PS3.17 2021c - Explanatory Information

IIII Encapsulated STL (Informative) (Current)
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# IIII Encapsulated STL (Informative)

The goal of encapsulating a Stereolithography (STL) 3D manufacturing model file inside a DICOM instance rather than transforming the data into a different representation is to facilitate preservation of the STL file in the exact form that it is used with extant manufacturing devices, while at the same time unambiguously associating it with the patient for whose care the model was created and the images from which the model was derived.

## IIII.1 Example of CT Derived Encapsulated STL

In this example, the patient requires a replacement implant for a large piece of skull on the left side of his head. A 3D manufacturing model (encoded in binary STL) was created by mirroring the corresponding section of the patient's right skull hemisphere, and then modified by trimming to fit the specific implantation area.

The model was derived from a series of CT images (CT-01). The STL data in this example is the first version, having no predecessor. The STL data was created on November 22, 2017 at 7:10:14 AM and then stored in a DICOM instance at 7:15:23 AM. The CT images were acquired weeks earlier.

The STL data was created in the coordinate system of CT-01; so they share the same Frame of Reference UID value.

A preview image (optional) showing the rendered 3D object was created and included with the encapsulated STL as an icon image.

No burned in annotation identifying the patient was included. The region of the skull reconstructed in the model contains no distinguishing facial features of the patient.

Table IIII.1-1. CT Derived Encapsulated STL Example

Attribute Name | Tag | Example Value | Comments
--- | --- | --- | ---
<Patient and General Study Modules not shown for brevity>
Modality | (0008,0060) | M3D |
Series Instance UID | (0020,000E) | 2.999.89235.5951.35894.0047 |
Series Number | (0020,0011) | 3 |
Series Description | (0008,103E) | Skull plate |
Instance Number | (0020,0013) | 1 |
Frame of Reference UID | (0020,0052) | 1.2.3.4.5.6.7.8.99 |
Manufacturer | (0008,0070) | Acme Additive Inc |
Manufacturer's Model Name | (0008,1090) | Implant Maker |
Device Serial Number | (0018,1000) | 00004367 |
Software Versions | (0018,1020) | 3.0.1 |
Content Date | (0008,0023) | 20171122 |
Content Time | (0008,0033) | 071014 |
Acquisition DateTime | (0008,002A) | 20171122071014 |
Image Laterality | (0020,0062) | L |
Burned In Annotation | (0028,0301) | NO |
Recognizable Visual Features | (0028,0302) | NO |
Source Instance Sequence | (0042,0013) |  | A sequence referencing the CT-01 source images
%item |  |  |
>Referenced SOP Class UID | (0008,1150) | 1.2.840.10008.5.1.4.1.1.2.1 | Referenced object is an Enhanced CT Image Storage Instance
>Referenced SOP Instance UID | (0008,1155) | 2.999.89235.5951.35894.155 | The multi-frame CT instance from study CT-01
>Purpose of Reference Code Sequence | (0040,A170) | (121324, DCM, "Source image") | CID 7060 “Encapsulated Document Source Purposes of Reference”
%enditem |  |  |
Document Title | (0042,0010) | CT 3D CAM model |
Concept Name Code Sequence | (0040,A043) | (85040-4, LN, "CT 3D CAM model") | CID 7061 “Model Document Titles”
MIME Type of Encapsulated Document | (0040,0012) | model/stl |
Encapsulated Document | (0042,0011) | <Byte stream representing the binary STL file> | Note that ASCII STL files are not supported.
Content Description | (0070,0081) | Mirrored and trimmed skull plate model from CT |
Measurement Units Code Sequence | (0040,08EA) | (mm, UCUM, "mm") |
Model Modification | (0068,7001) | YES |
Model Mirroring | (0068,7002) | YES | In this example, mirroring (from the right side) was performed to create the object.
Model Usage Code Sequence | (0068,7003) | (129016, DCM, "Implant Fabrication") | CID 7064 “Model Usage” In this example, the goal is to implant the object in the patient.
Icon Image Sequence | (0088,0200) |  | Sequence containing the pre-rendered preview image
%item |  |  |
<Content of Table C.7-11b "Image Pixel Macro Attributes" not shown>
%enditem |  |  |
SOP Class UID | (0008,0016) | 1.2.840.10008.5.1.4.1.1.104.3 |
SOP Instance UID | (0008,0018) | 1.2.3.4.5.6.7.88.901 |
Instance Creation Date | (0008,0012) | 20171122 |
Instance Creation Time | (0008,0013) | 071523 |

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HHHH Protocol Approval Examples and Concepts (Informative) | Home | IIII.2 Example of Fused CT/MR Derived Encapsulated STL

DICOM PS3.17 2021c - Explanatory Information