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Page 196​ DICOM PS3.3 2020a - Information Object Definitions​

Table 10.38-1. Outline Definition Macro Attributes​

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non-intersecting except at the vertices. Any given vertex shall occur only​ once in the data stream.​

Required if Outline Shape Type (0018,1630) is POLYGONAL.​

The number of pairsin this data stream shall equal the value ofNumber​ of Polygonal Vertices (0018,1637).​

See Section 10.38.1.2.​

10.38.1 Outline Definition Macro Attribute Description​

10.38.1.1 Outline Shape Type​

When outline shape is a rectangle or a circle per design, the Outline Shape Type (0018,1630) shall have the value RECTANGULAR​ or CIRCULAR respectively and the outline shall not be represented as a polyline.​

10.38.1.2 Coordinate Definitions​

The values are defined in a plane that is declared in the invocation of the Macro.​

10.39 Patient to Equipment Relationship Macro​

The Patient to Equipment Relationship Macro describes a position of the patient with respect to a device. The position is defined by​ means of a transformation matrix between a Patient Frame of Reference and an Equipment Frame of Reference.​

Table 10.39-1. Patient to Equipment Relationship Macro Attributes​

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See Section 10.39.1.2.​

Zero or one Item shall be included in this Sequence.​

>Include Table 10.40-1 “Patient Support Position Macro Attributes”.​

10.39.1 Patient to Equipment Relationship Macro Attributes Description​

10.39.1.1 Equipment Coordinate System​

A piece of equipment has an Equipment Coordinate System which can be used for expressing geometric concepts such as locations​ andorientations.Thecoordinatesystemischaracterizedbythelocationoftheoriginandtheorientationofcoordinateaxeswithrespect​ to the equipment. The Equipment Coordinate System is a right-handed coordinate system.​

Equipment Coordinate Systems are typically based on a standardized definition of axes. The choice of origin is often device-specific​ or device-type-specific. It may be any significant location on the machine such as the manufacturer-dependent machine isocenter.​

The Equipment Coordinate System can be used as the parent for derived coordinate systems.​

10.39.1.2 Image to Equipment Mapping Matrix and Patient Support Position Macro​

The Image to Equipment Mapping Matrix (0028,9520) describes the relationship between the Patient-oriented coordinate system and​ an Equipment Coordinate System. This matrix AM Bdescribes a rigid transformation of a point ( Bx, By, Bz) with respect to the Patient​ coordinate system into ( Ax, Ay, Az) with respect to the Equipment Coordinate System as defined in Section C.7.6.21.1.​

The Equipment Coordinate System is identified by the Equipment Frame of Reference UID (300A,0675). For further information on​ the definition of the Equipment Frame of Reference, see Section 10.39.1.1. The patient-oriented coordinate system is identified by​ the Frame of Reference UID (0020,0052) of the SOP Instance it is used within. Both coordinate systems are expressed in millimeters.​

The Patient Support Position Macro invoked by Patient Support Position Sequence (3006,00CB) allows the exchange of device-​ specific parameters for the patient support device. Applications designed to guide a specific patient support device will be able to de-​ compose the transformation into device-specific parameters or derive a transformation matrix out of these parameters. Applications​ that are unable to know the decomposition of the transformation to those parameters and vice versa will still be able to display the​ native labels and numerical values of those parameters to human readers.​

The Patient Support Position Sequence (3006,00CB) may be present to annotate the matrix and display the decomposed matrix​ contents. The content of the Patient Support Position Macro shall be used for display purposes only. It shall not be used for other​ purposes. The content of this Macro shall not be used as a substitute for the Image to Equipment Mapping Matrix (0028,9520). In​ general,thereismorethanonewaytoreachthepointinspacethatisdescribedbytheImagetoEquipmentMappingMatrix(0028,9520).​ Hence it is explicitly not implied how this position is reached.​

In some cases (e.g., emergency treatments in Radiotherapy), the Patient Frame of Reference is not defined by an image series. In​ this case an arbitrary Frame of Reference is used for the patient coordinate system in the Frame of Reference Module of the SOP​ instance. The Image to Equipment Mapping Matrix (0028,9520) has the same meaning as in the case of image-based Patient Frame​ of Reference.​

If the Image to Equipment Mapping Matrix (0028,9520) and the Patient Support Position Sequence (3006,00CB) are both present,​ the information in both locations shall be consistent.​

10.40 Patient Support Position Macro​

This Macro provides the device-specific geometric settings for the Patient Support device.​

The information is intended for display to human readers and to support non-image-based patient positioning; however, the definition​ of the patient position with respect to the device is contained in the Image to Equipment Mapping Matrix (0028,9520).​

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DICOM PS3.3 2020a - Information Object Definitions​ Page 199​

Table 10.40-1. Patient Support Position Macro Attributes​

10.40.1 Position Parameters and Order Index​

The Device Order Index (300A,065E) and thePatient Support Position Parameter Order Index (300A,065F) are applied sequentially,​ meaning all the Items in a Patient Support Position Parameter Sequence (300A,065B) are applied before proceeding to the Item in​ the Patient Support Position Device Parameter Sequence (300A,065D) specified by the next Device Order Index (300A,065E) value.​

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A vendor may specify codes that are not included in TID 175001 and/or a set of codes which is not identical with the set defined in​ Section 10.40.1.1 or Section 10.40.1.2. The vendor shall document the codes used in this Macro in the Conformance Statement, as​ well as the corresponding parameters, their geometric interpretation, and the order in which they will be applied. These parameters​ shall use UCUM units of mm for lengths and degrees for angles.​

10.40.1.1 IEC 61217 Patient Support Device​

Devices using the IEC 61217 coordinate systems to define geometric settings for the Patient Support device shall use the codes in​ Table 10.40-2 in the order specified in column Patient Support Position Parameter Order Index (300A,065F). Other codes shall not​ be used.​

Table 10.40-2. Isocentric Patient Support Position Parameter Order Index​

10.40.1.2 Isocentric Patient Support Device​

DevicesusinganisocentricrepresentationtodefinegeometricsettingsforthePatientSupportdeviceshallusethecodesinTable10.40-​ 3 in the order specified in column Patient Support Position Parameter Order Index (300A,065F). Other codes shall not be used.​

Table 10.40-3. Isocentric Patient Support Position Parameter Order Index​

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