The Image to Equipment Mapping Matrix (0028,9520) is used to describe the relationship between the Patient oriented coordinate system and a modality specific equipment coordinate system. This mapping can only be used with systems that have a well-defined equipment coordinate system (such as XA, etc.).

The Image to Equipment Mapping Matrix
^{
A
}
M
_{
B
}
describes how to transform a point (
^{
B
}
x,
^{
B
}
y,
^{
B
}
z) with respect to the Patient coordinate system into (
^{
A
}
x,
^{
A
}
y,
^{
A
}
z) with respect to the equipment coordinate system according to the equation below.

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Error! Not a valid embedded object.
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The Image to Equipment Mapping Matrix is a rigid transformation that involves only translations and rotations. Mathematically, the matrix shall be orthonormal and can describe six degrees of freedom: three translations, and three rotations.

Note: Both the Patient Coordinate System and the Equipment Coordinate System are expressed in millimeters.

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C.7.6.21.2 Equipment Coordinate System Identification
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The Equipment Coordinate System Identification (0028,9537) identifies the Reference Coordinate System to which the Image to Equipment Mapping Matrix (0028,9520) is related.

The Defined Term ISOCENTER refers to a coordinate reference system where the origin corresponds with the center of rotation of the projections.

Note: For X-Ray 3D Angiographic Images created from SOP Instances of the Enhanced XA SOP Class (1.2.840.10008.5.1.4.1.1.12.1.1) the isocenter coordinate system is used to describe the positioning of the table and positioner (see C.8.19.6.13), and will use only the Defined Term ISOCENTER.