Ophthalmic Anatomic Reference Point X-Coordinate Attribute
| Tag | (0022,1624) |
|---|---|
| Type | Conditionally Required, Empty if Unknown (2C) |
| Keyword | OphthalmicAnatomicReferencePointXCoordinate |
| Value Multiplicity | 1 |
| Value Representation | Single (FL) |
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.
Section C.8.17.5.1
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
Figure C.10.5-1
Figure C.10.5-1. Sub-pixel Addressing Units in PIXEL Space