Материал: part03

C.8.30.3.1.3 Source Image Corneal Processed Data Sequence​

The Source Image Corneal Processed Data Sequence (0046,0244) provides power, elevation and wavefront measurements taken​ at specific points of the Source Image. These Attributes were used to generate the corneal topography map and indices of this SOP​ Instance. This processed data can also be used to generate other corneal topography maps and indices.​

C.8.30.3.1.4 Corneal Vertex Location​

TheCornealVertexLocation(0046,0202)establishesthereferencepointforthecornealvertex,theoriginoftheOphthalmicCoordinate​ System.TheOphthalmicCoordinateSystemisusedastheFrameofReferencethatestablishesthespatialrelationshipforthecorneal​ vertex (i.e., used within corneal topography maps) for a set of Images within a Series. It also allows Images across multiple Series​ to share the same Frame Of Reference. The corneal vertex is the point located at the intersection of the patient's line of sight (visual​ axis) and the corneal surface. It is represented by the corneal light reflex when the cornea is illuminated coaxially with fixation.​

Note​

Since the criteria used to group images into a Series is application specific, it is possible for imaging applications to define​ multiple Series within a Study that share the same imaging space. Therefore the images with the same Frame of Reference​ UID (0020,0052) Attribute value share the same corneal vertex location within the patient's eye.​

Figure C.8.30.3.1-3 illustrates the representation of corneal topography. The corneal vertex lies at the center of the rulers. Typical​ circular grids are 3, 5, 7, and 9 mm diameters centered on the vertex. The annotations in Figure C.8.30.3.1-3 are R, right; L, left; H​ = Head; F = Foot.​

H H

R L R L

F F

R L

Figure C.8.30.3.1-3. Representation of Corneal Topography​

Numerical position data shall use the Cartesian (i.e., two dimensional rectangular) coordinate system. The direction of the axes are​ determined by Patient Orientation (0020,0020), see Section C.7.6.1.1.1 for further explanation.​

Devices that internally capture data in polar coordinates will need to convert to Cartesian coordinates, see Figure C.8.30.3.1-4.​

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Figure C.8.30.3.1-4. Sample Coordinate Data Points​

When using the 3 dimensional coordinates (X, Y, Z), the Z axis shall represent corneal elevation. Z shall be measured from the length​ of a vector normal to the plane that is normal to and intersects the corneal vertex at the intersection of the x, y, z, axes. It is shown​ in the diagram as "+" (0.0, 0.0, 0.0). The Z axis shall be positive towards the anterior direction of the eye; (i.e., it is a right-hand rule​ coordinate system. Thus the Z values (see Figure C.8.30.3.1-5 and Figure C.8.30.3.1-6) will be predominantly negative, as they are​ posterior to the plane of the corneal vertex.​

Figure C.8.30.3.1-5. Schematic of the 3-Dimensional Representation of Corneal Elevation​

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Y

X

Z

FigureC.8.30.3.1-6.SchematicoftheOphthalmicCoordinateSystemofthe3-DimensionalRepresentation​

used in Wide Field Measurements​

C.8.31 Breast Projection Image Modules​

C.8.31.1 Enhanced Mammography Image Module​

Table C.8.31-1 specifies the Attributes that identify and describe general information about the Enhanced Mammography Image​ Module.​

Table C.8.31-1. Enhanced Mammography Image Module Attributes​

started.​

Note​

The synchronization of this time with an external clock is​ specified in the Synchronization Module in Acquisition Time​ Synchronized (0018,1800).​

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AUTOMATIC​

MANUAL​

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Enumerated Values:​

8​

9​

10​

11​

12​

13​

14​

15​

16​

Enumerated Values:​

0000H​unsigned integer​

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