Материал: part03

For an Ophthalmic Coordinate System, the Frame of Reference is based upon the corneal vertex. The corneal vertex is determined​ by the measuring instrument and shall be identified in this Attribute with the value CORNEAL_VERTEX_R (for the right eye) or​ CORNEAL_VERTEX_L (for the left eye). The Ophthalmic Coordinate System is described in Section C.8.30.3.1.4.​

The Position Reference Indicator shall be used only for annotation purposes and is not intended to be used as a mathematical spatial​ reference.​

Note​

The Position Reference Indicator may be encoded as zero length when it has no meaning, for example, when the Frame of​ Reference Module is required to relate mammographic images of the breast acquired without releasing breast compression,​ but where there is no meaningful anatomical reference point as such.​

C.7.4.2 Synchronization Module​

Table C.7-7 specifies the Attributes necessary to uniquely identify a Frame of Reference that establishes the temporal relationship​ of SOP Instances. A synchronized environment may be established based on a shared time of day clock, and/or on a shared trigger​ event or synchronization waveform channel.​

Note​

Within a synchronized environment, different devices may use the shared data differently. An electrical pulse, for example,​ may be treated as a trigger event by one device (e.g., an X-Ray imaging system), but may be recorded as a synchronization​ waveform by another device (e.g., a hemodynamics system).​

Table C.7-7. Synchronization Module Attributes​

- Standard -​

indotteddecimal(e.g.,192.168.1.1).TheIPv6addressesshallbeincolon​ separated hexadecimal (e.g., 12:34:56:78:9a:bc:de:f0).​

Note​

Identityofthisvalueintwoinstancesacquiredcontemporaneously​ implies a common time base. The NTP Source Address might​ not persist over time.​

C.7.4.2.1 Synchronization Attribute Descriptions​

C.7.4.2.1.1 Synchronization Frame of Reference UID​

A set of equipment may share a common acquisition synchronization environment, which is identified by a Synchronization Frame​ of Reference UID. All SOP Instances that share the same Synchronization Frame of Reference UID shall be temporally related to​ each other. If a Synchronization Frame of Reference UID is present, all SOP Instances in the Series must share the same Frame of​ Reference.​

The UTC Synchronization UID, 1.2.840.10008.15.1.1, may be used when the equipment is synchronized to the international standard​

UTC. In this case the quality of synchronization may be determined by means of the Time Distribution Protocol (0018,1802) and NTP​

Source Address (0018,1803).​

Note​

1.​The Synchronization Frame of Reference UID defines an equipment synchronization environment, and does not need​ tobechangedforeachunrelatedacquisition.SOPInstancesmaythereforeshareaSynchronizationFrameofReference​ UID, but be clinically unrelated (e.g., apply to different Patients).​

2.​When a synchronization environment is recalibrated, a new UID must be issued.​

3.​The method of distributing the Synchronization Frame of Reference UID to multiple devices is not specified.​

C.7.4.2.1.2 Time Source and Time Distribution Protocol​

Time may originate with a primary source (e.g., a national standards bureau) and be distributed through a chain of secondary distri-​ bution systems until reaching the imaging equipment. Time Distribution Protocol (0018,1802) specifies the immediate (last link)​ method used by the equipment to receive time from the immediately prior Time Source (0018,1801). It does not specify the ultimate​ time reference from which the Time Source may derive its synchronization.​

Note​

The time value distributed through the specified Time Distribution Protocol may need to be corrected to align with UTC. For​ example, GPS does not compensate for leap seconds.​

C.7.4.2.1.3 Synchronization Channel​

Synchronization Channel (0018,106C) is specified as a pair of values (M,C), where the first value is the ordinal of the Sequence Item​ of Waveform Sequence (5400,0100) (i.e., the Multiplex Group), and the second value is the ordinal of the Sequence Item of the​ Channel Definition Sequence (003A,0200) Attribute (i.e., the Waveform Channel Number) within the multiplex group.​

- Standard -​

C.7.4.2.1.4 Acquisition Time Synchronized​

The Acquisition Time Synchronized (0018,1800) Attribute specifies whether Acquisition DateTime (0008,002A) of the Waveform​ IdentificationModuleortheGeneralImageModulerepresentsanaccuratesynchronizedtimestampfortheacquisitionofthewaveform​ and/or image data. For triggered multi-frame images, the Acquisition DateTime applies to the trigger for the first image frame (see​ Attribute Image Trigger Delay (0018.1067) in the Cine Module).​

Note​

The degree of precision of the Acquisition DateTime and its accuracy relative to the external clock are not specified, but​ need to be appropriate for the clinical application.​

For IODs that include the SR Document Content Module, the Acquisition Time Synchronized (0018,1800) Attribute specifies whether​ Observation DateTime (0040,A032) of Items in Content Sequence (0040,A730) of the SR Document Content Module represents an​ accurate synchronized timestamp for the Item.​

C.7.5 Common Equipment IE Modules​

The following Equipment IE Module is common to all Composite IODs that reference the Equipment IE.​

C.7.5.1 General Equipment Module​

Table C.7-8 specifies the Attributes that identify and describe the piece of equipment that produced a Series of Composite Instances.​

Table C.7-8. General Equipment Module Attributes​

- Standard -​

- Standard -​

Required if Pixel Padding Range Limit (0028,0121) is present and either Pixel​ Data (7FE0,0010) or Pixel Data Provider URL (0028,7FE0) is present. May​ be present otherwise only if Pixel Data (7FE0,0010) or Pixel Data Provider​ URL (0028,7FE0) is present.​

Note​

1.​The Value Representation of this Attribute is determined by the​ value of Pixel Representation (0028,0103).​

2.​This Attribute is not used in Presentation State Instances; there​ is no means in a Presentation State to "override" any Pixel​ Padding Value specified in the referenced images.​

3.​This Attribute does apply to RT Dose and Segmentation​ instances, since they include Pixel Data.​

4.​ThisAttributedoesnotapplywhenFloatPixelData(7FE0,0008)​ orDoubleFloatPixelData(7FE0,0009)areusedinsteadofPixel​ Data (7FE0,0010); Float Pixel Padding Value (0028,0122) or​ DoubleFloatPixelPaddingValue(0028,0123),respectively,are​ usedinstead,anddefinedattheImage,nottheEquipment,level.​

C.7.5.1.1 General Equipment Attribute Descriptions​

Note​

The Attributes Manufacturer (0008,0070), Manufacturer's Model Name (0008,1090) and Device Serial Number (0018,1000)​ are intended to be a primary identification of the system that produces the data (e.g., modality or workstation application​ providing the content of the SOP Instance) and not the identification of the component that encodes the SOP Instance (e.g.,​ a commonly used DICOM encoding toolkit).​

C.7.5.1.1.1 Date of Last Calibration, Time of Last Calibration​

Date of Last Calibration (0018,1200) and Time of Last Calibration (0018,1201) are used to convey the date and time of calibration.​ The Attribute Date of Last Calibration (0018,1200) may be supported alone, however, Time of Last Calibration (0018,1201) Attribute​ has no meaning unless Attribute Date of Last Calibration (0018,1200) is also supported. The order for each Attribute shall be from​ the oldest date/time to the most recent date/time. When the Attributes are both supported they shall be provided as pairs.​

C.7.5.1.1.2 Pixel Padding Value and Pixel Padding Range Limit​

Pixel Padding Value (0028,0120) is used to pad grayscale images (those with a Photometric Interpretation of MONOCHROME1 or​ MONOCHROME2) to rectangular format. The native format of some images is not rectangular. It is common for devices with this​ format to pad the images to the rectangular format required by the DICOM Standard with a specific pixel value that is not contained​ in the native image. Further, when resampling, such as after spatial registration, padding may need to be used to fill previously non-​ existent pixels.​

- Standard -​