UUUU.4.5.3 X-Ray Isocenter Reference System in Traditional RDSR

UUUU.4.5.3 X-Ray Isocenter Reference System in Traditional RDSR (Current)
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A complete geometric description of the equipment components within the same coordinates system is required for a complete understanding of dose distribution and potential patient impact.

In the RDSR Instances, when the Reference Point is defined with respect to the Isocenter, the position of the table supporting the patient should also be defined with respect to that Isocenter to allow relating the Reference Point to the surface of the patient laying on the table.

The Content Items for the Table Longitudinal, Lateral, and Height Positions in the Traditional RDSR are defined with respect to an arbitrary coordinate system which is not necessarily related to the Isocenter. To overcome this limitation, the Traditional RDSR also encodes table positions in the X-Ray Isocenter Coordinate System following the definitions in Section C.8.19.6.13 X-Ray Isocenter Reference System Macro in PS3.3 , for equipment that implements the X-Ray Isocenter Reference System model.

Also refer to Annex Z and Section FFF.2.1.3 for additional examples of the X-Ray Isocenter Reference System model.

Table UUUU.4.5.3-1 shows the encoding of the X-Ray Isocenter Reference System in Traditional RDSR.

Table UUUU.4.5.3-1. Example of Encoding X-Ray Isocenter Reference System in Traditional RDSR

NL	Concept Name	Example Value	TID
	(113706, DCM, "Irradiation Event X-Ray Data")		TID 10003
…
>	(128757, DCM, "Positioner Isocenter Primary Angle")	30.0 deg	TID 10003C
>	(128758, DCM, "Positioner Isocenter Secondary Angle")	0.0 deg	TID 10003C
>	(128759, DCM, "Positioner Isocenter Detector Rotation Angle")	90.0 deg	TID 10003C
>	(128760, DCM, "Positioner Isocenter Primary End Angle")	-10.0 deg	TID 10003C
>	(128761, DCM, "Positioner Isocenter Secondary End Angle")	0.0 deg	TID 10003C
>	(128762, DCM, "Positioner Isocenter Detector Rotation End Angle")	90.0 deg	TID 10003C
>	(113754, DCM, "Table Head Tilt Angle")	0.0 deg	TID 10003C
>	(113755, DCM, "Table Horizontal Rotation Angle")	0.0 deg	TID 10003C
>	(113756, DCM, "Table Cradle Tilt Angle")	0.0 deg	TID 10003C
>	(128763, DCM, "Table Head Tilt End Angle")	0.0 deg	TID 10003C
>	(128764, DCM, "Table Horizontal Rotation End Angle")	0.0 deg	TID 10003C
>	(128765, DCM, "Table Cradle Tilt End Angle")	0.0 deg	TID 10003C
Next rows are multiple inclusions drawn from CID 10008 “Dose Related Distance Measurement”
>	(128766, DCM, "Table X Position to Isocenter")	50.0 mm	TID 10003C
>	(128767, DCM, "Table Y Position to Isocenter")	150.0 mm	TID 10003C
>	(128768, DCM, "Table Z Position to Isocenter")	400.0 mm	TID 10003C
>	(128769, DCM, "Table X End Position to Isocenter")	50.0 mm	TID 10003C
>	(128770, DCM, "Table Y End Position to Isocenter")	150.0 mm	TID 10003C
>	(128771, DCM, "Table Z End Position to Isocenter")	400.0 mm	TID 10003C

Additionally, there are Content Items in TID 10002 to relate the patient position to the X-Ray Table, which in turn allows relating the Isocenter Reference Point (and the Dose Reference Point) to the patient laying on the table.

UUUU.4.5.3.1 Equipment Landmark

The Equipment Landmark is a point used as spatial reference in the Table Reference System. It establishes a visible location on the X-Ray Table that allows the operator to measure distances from that point to one or more parts of the patient body.

TID 10002 uses (128751, DCM, "Center of Table Head") as the Equipment Landmark.

The Equipment Landmark is defined in the Table Coordinate System by its coordinates X and Z, encoded as (128752, DCM, "Equipment Landmark X Position") and (128753, DCM, "Equipment Landmark Z Position").

The Equipment Landmark Y Position is not recorded, its value is zero by definition since (128751, DCM, "Center of Table Head") is defined as being in the plane of the table.

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UUUU.4.5.2 Equipment Geometry in Traditional RDSR	Home	UUUU.4.5.3.2 Patient Fiducials