Equipment Frame of Reference UID Attribute
| Tag | (300A,0675) |
|---|---|
| Type | Conditionally Required (1C) |
| Keyword | EquipmentFrameOfReferenceUID |
| Value Multiplicity | 1 |
| Value Representation | Unique Identifier (UI) |
Frame of Reference identifier for the Treatment Delivery Device defining the coordinate system in which the geometric parameters are defined.
Required if Image to Equipment Mapping Matrix (0028,9520) or Device Position to Equipment Mapping Matrix (3002,010F) are present in the current SOP Instance.
See Section C.36.12.1.1.
Section C.36.12.1.1
C.36.12.1.1 Equipment Frame of Reference UID
The Equipment Frame of Reference UID (300A,0675) identifies the Equipment Coordinate System for a Treatment Delivery Device, see Section 10.39.1.1.
The RT Radiation SOP Classes are bound by the Standard to specific Well-known Frames of Reference as defined in Table A-2 in PS3.6 . For C-Arm based devices delivering radiation at a single machine isocenter this may be the [IEC 61217] coordinate system. Devices are calibrated to a specific Well-known Frame of Reference and thus use the corresponding Well-known UID in Equipment Frame of Reference UID (300A,0675).
For RT Radiation SOP Classes the result of the transformation between the Patient-based Coordinate System and the Equipment Coordinate System is used to describe the intended treatment position. If two or more transformation matrices describe the relation between two or more Patient-based coordinate systems and a single Equipment Coordinate System, any calculations assuming transitivity via the Equipment Coordinate System must be performed with great care because the patients anatomy may have changed.
For RT Radiation Record SOP Classes the result of the transformation between the Patient-based Coordinate System and the Equipment Coordinate System is used to describe the actual treatment position. In this case the transformation matrices between different Patient-Based coordinate Systems and a single Equipment Coordinate System shall not be considered transitive from an anatomical point of view and may only be used to compare different treatment positions with respect to the treatment delivery device.