Range of Angular Values using IEC Geometry Definitions



DICOM Correction Proposal

|STATUS |Assigned |

|Date of Last Update |2013/10/18 |

|Person Assigned |Ulrich Busch (ulrich.busch@) |

|Submitter Name |Ulrich Busch (ulrich.busch@) |

|Submission Date |2013/03/01 |

|Correction Number CP-1328 |

|Log Summary: Range of Angular Values using IEC Geometry Definitions |

|Name of Standard |

|PS3 2011 |

|Rationale for Correction: |

|RT object use IEC 61217 in some attributes to define device geometries. However, there was some confusion about whether this includes the |

|restrictions of values ranges as spelled out in IEC 61217. Those value range constraint in IEC 61217 apply only to user interface displays and |

|do not apply to value representation in internal storages of data exchange protocols. In contrary, some RT modalities have need for values |

|outside the range of user display rules in IEC 61217. This section clarifies the situation. |

|At the same time. A new appendix is introduced to Part 17 to handle Radiotherapy topics. |

|Correction Wording: |

In PS3.3, section C.8.8.14 RT Beams Module, add the following text:

C.8.8.14 RT Beams Module

Table C.8-50—RT BEAMS MODULE ATTRIBUTES

|Attribute Name |Tag |Type |Attribute Description |

|... | | | |

|>Control Point Sequence |(300A,0111) |1 |Introduces sequence of machine configurations describing |

| | | |treatment beam. |

| | | |Two or more items shall be included in this sequence. |

| | | |See C.8.8.14.5 and C.8.8.14.6. |

|... | | | |

|>>Gantry Angle |(300A,011E) |1C |Gantry angle of radiation source, i.e. orientation of IEC |

| | | |GANTRY coordinate system with respect to IEC FIXED |

| | | |REFERENCE coordinate system (degrees). Required for first |

| | | |item of Control Point Sequence, or if Gantry Angle changes |

| | | |during Beam. |

| | | |See C.8.8.14.12 |

|… | | | |

|>>Gantry Pitch Angle |(300A,014A) |3 |Gantry Pitch Angle. i.e. the rotation of the IEC GANTRY |

| | | |coordinate system about the X-axis of the IEC GANTRY |

| | | |coordinate system (degrees). If used, must be present for |

| | | |first item of Control Point Sequence, or if used and Gantry|

| | | |Pitch Rotation Angle changes during Beam, must be present. |

| | | |See C.8.8.25.6.5. |

| | | |See C.8.8.14.12 |

|… | | | |

|>>Beam Limiting Device Angle |(300A,0120) |1C |Beam Limiting Device angle, i.e. orientation of IEC BEAM |

| | | |LIMITING DEVICE coordinate system with respect to IEC |

| | | |GANTRY coordinate system (degrees). Required for first item|

| | | |of Control Point Sequence, or if Beam Limiting Device Angle|

| | | |changes during Beam. |

| | | |See C.8.8.14.12 |

|… | | | |

|>>Patient Support Angle |(300A,0122) |1C |Patient Support angle, i.e. orientation of IEC PATIENT |

| | | |SUPPORT (turntable) coordinate system with respect to IEC |

| | | |FIXED REFERENCE coordinate system (degrees). Required for |

| | | |first item of Control Point Sequence, or if Patient Support|

| | | |Angle changes during Beam. |

| | | |See C.8.8.14.12 |

|… | | | |

|>>Table Top Eccentric Angle |(300A,0125) |1C |Table Top (non-isocentric) angle, i.e. orientation of IEC |

| | | |TABLE TOP ECCENTRIC coordinate system with respect to IEC |

| | | |PATIENT SUPPORT coordinate system (degrees). Required for |

| | | |first item of Control Point Sequence, or if Table Top |

| | | |Eccentric Angle changes during Beam. |

| | | |See C.8.8.14.12 |

|… | | | |

|>>Table Top Pitch Angle |(300A,0140) |1C |Table Top Pitch Angle, i.e. the rotation of the IEC TABLE |

| | | |TOP coordinate system about the X-axis of the IEC TABLE TOP|

| | | |coordinate system (degrees). If required by treatment |

| | | |delivery device, shall be present for first item of Control|

| | | |Point Sequence. If required by treatment delivery device |

| | | |and if Table Top Pitch Angle changes during Beam, shall be |

| | | |present in all subsequent items of Control Point Sequence. |

| | | |See C.8.8.25.6.2 and C.8.8.14.12 |

|… | | | |

|>>Table Top Roll Angle |(300A,0144) |1C |Table Top Roll Angle, i.e. the rotation of the IEC TABLE |

| | | |TOP coordinate system about the IEC Y-axis of the IEC TABLE|

| | | |TOP coordinate system (degrees). If required by treatment |

| | | |delivery device, shall be present for first item of Control|

| | | |Point Sequence. If required by treatment delivery device |

| | | |and if Table Top Roll Angle changes during Beam, shall be |

| | | |present in all subsequent items of Control Point Sequence. |

| | | |See C.8.8.25.6.2 and C.8.8.14.12 |

|… | | | |

…

C.8.8.14.11 Block and Compensator Precedence for Dosimetric Calculations

If Block Thickness (300A,0100) and Block Transmission (300A,0102) are present, Block Transmission shall have precedence for dosimetric calculations. If Compensator Transmission Data (300A,00EB) and Compensator Thickness Data (300A,00EC) are present, Compensator Transmission Data shall have precedence for dosimetric calculations.

C.8.8.14.12 Angular Values in RT Beams Module

Attributes having Angular Value refer to the IEC coordinate system defined in IEC 61217 where indicated. The reference to a certain IEC coordinate system defines the orientation of the rotation axis and the origin of the rotating coordinate system. However, the reference of IEC 61217 does not imply a restriction of the range of numerical values permitted in those attributes. IEC 61217 has certain restrictions of the range of value specified; but they apply explicitly to user interface representation only. The DICOM Standard does not make use of those definitions. Therefore the range of angular values is not restricted to any specific limits.

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