DICOM PS3.3 2021b - Information Object Definitions

C.8.17.5 Ocular Region Imaged Module (Current)
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#### C.8.17.5 Ocular Region Imaged Module

Table C.8.17.5-1 contains IOD Attributes that describe the anatomy imaged in an Ophthalmic Photography or Ophthalmic Tomography Image Storage SOP Instance.

Table C.8.17.5-1. Ocular Region Imaged Module Attributes

Attribute Name | Tag | Type | Attribute Description
--- | --- | --- | ---
Image Laterality | (0020,0062) | 1 | Laterality of object imaged (as described in Anatomic Region Sequence (0008,2218)) examined. Enumerated Values: R right eye L left eye B both left and right eye Shall be consistent with any laterality information contained in Primary Anatomic Structure Modifier Sequence (0008,2230), if present. ### Note Laterality (0020,0060) is a Series level Attribute and must be the same for all Images in the Series, hence it must be absent if Image Laterality (0020,0062) has different values for Images in the same Series. Since most Ophthalmic Photographic Image Series contain images of both eyes, the Series level Attribute will rarely be present.
Relative Image Position Code Sequence | (0022,001D) | 2C | The position of this image on the retina (as defined by a specified nomenclature; the nomenclature is implicit in the code used). Only a single Item is permitted in this Sequence. Required if Ophthalmic Volumetric Properties Flag (0022,1622) is set to YES and Attributes Ophthalmic Anatomic Reference Point X-Coordinate (0022,1624) and Ophthalmic Anatomic Reference Point Y-Coordinate (0022,1626) do not contain a value. May be present otherwise. ### Note This Attribute is used to provide the user with a general reference point when viewing the image. If the implementation is able to identify a precise anatomic location, it will convey that information in Attributes Ophthalmic Anatomic Reference Point X-Coordinate (0022,1624) and Ophthalmic Anatomic Reference Point Y-Coordinate (0022,1626).
>Include Table 8.8-1 “Code Sequence Macro Attributes” | BCID 4207 “Ophthalmic Image Position”.
Ophthalmic Anatomic Reference Point X-Coordinate | (0022,1624) | 2C | The horizontal offset location (column) of the anatomic reference point identified by Attribute Primary Anatomic Region Sequence (0008,2228). See Section C.8.17.5.1 for further explanation. Image relative position specified with sub-pixel resolution such that the origin at the Top Left Hand Corner (TLHC) of the TLHC pixel is 0.0\0.0, the Bottom Right Hand Corner (BRHC) of the TLHC pixel is 1.0\1.0, and the BRHC of the BRHC pixel is Columns\Rows (see Figure C.10.5-1). The value must be within the range 0\0 to Columns. Required if Ophthalmic Volumetric Properties Flag (0022,1622) is set to YES. May be present otherwise.
Ophthalmic Anatomic Reference Point Y-Coordinate | (0022,1626) | 2C | The vertical offset location (row) of the anatomic reference point identified by Attribute Primary Anatomic Region Sequence (0008,2228). See Section C.8.17.5.1 for further explanation. Image relative position specified with sub-pixel resolution such that the origin at the Top Left Hand Corner (TLHC) of the TLHC pixel is 0.0\0.0, the Bottom Right Hand Corner (BRHC) of the TLHC pixel is 1.0\1.0, and the BRHC of the BRHC pixel is Columns\Rows (see Figure C.10.5-1). The value must be within the range 0\0 to Rows. Required if Ophthalmic Volumetric Properties Flag (0022,1622) is set to YES. May be present otherwise.
Include Table 10-5 “General Anatomy Mandatory Macro Attributes” | DCID 4209 “Ophthalmic Anatomic Structure Imaged” for Anatomic Region Sequence. DCID 4266 “Ophthalmic Anatomic Structure Reference Point” for Primary Anatomic Structure Sequence. In this Module, Primary Anatomic Structure Sequence (0008,2228) is specialized to be Type 1C; required if Attributes Ophthalmic Anatomic Reference Point X-Coordinate (0022,0024) and Ophthalmic Anatomic Reference Point Y-Coordinate (0022,0026) contain a value; may be present otherwise.

##### C.8.17.5.1 Ocular Region Imaged Module Attribute Descriptions

###### C.8.17.5.1.1 Ophthalmic Anatomic Reference Point Location

The Attributes Ophthalmic Anatomic Reference Point X-Coordinate (0022,1624) and Ophthalmic Anatomic Reference Point Y-Coordinate (0022,1626) are used when an Ophthalmic Tomography Image Storage SOP Instance contains Attributes to convey volumetric properties (such as when using the Ophthalmic Tomography image for angiography). These Attributes identify the location of the anatomic region conveyed in Attribute Primary Anatomic Region Sequence (0008,2228). The most common anatomic regions identified for an OCT angiography are the fovea centralis and optic nerve head.

### Note

The Anatomic Region Sequence (0008,2218) is typically set to (81745001, SCT, "Eye").

Figure C.8.17.5-1 shows an Ophthalmic Tomography image displaying the fovea centralis. The image Row/Column is defined as 245 x 245 and the location of the fovea centralis is horizontal row = 194 and vertical row = 132. Therefore, Attribute Ophthalmic Anatomic Reference Point X-Coordinate (0022,0024) is equal to 194 and Attribute Ophthalmic Anatomic Reference Point Y-Coordinate (0022,0026) is equal to 132.

Figure C.8.17.5-1. En face Image - Ophthalmic Anatomic Reference Point Location Example

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DICOM PS3.3 2021b - Information Object Definitions