Материал: part03

C.8.9.4 PET Image Module​

Table C.8-63 contains IOD Attributes that describe PET images.​

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Page 872​ DICOM PS3.3 2020a - Information Object Definitions​

Table C.8-63. PET Image Module Attributes​

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Note​

Referenced Overlay Sequence (0008,1130) and Referenced Curve Sequence (0008,1145) were previously included in this​ Module as optional Attributes but have been retired. See PS3.3-2004.​

C.8.9.4.1 PET Image Module Attribute Descriptions​

C.8.9.4.1.1 Image Type​

For PET Images, Image Type (0008,0008) is specified to be Type 1.​

Note​

ForPETimages,ImageType(0008,0008)Value1willbeORIGINALforreconstructedimages.DERIVEDmaybeappropriate​ for some other results images. For PET images, Image Type (0008,0008) Value 2 will be PRIMARY.​

C.8.9.4.1.2 Photometric Interpretation​

Enumerated Values:​

MONOCHROME2​

See Section C.7.6.3.1.2 for definition of this term.​

C.8.9.4.1.3 Frame Time​

Frame Time (0018,1063) is the explicit duration of the gated frame when Cardiac Framing Type (0018,1064) is equal to FORW or​ BACK. Frame Time (0018,1063) is the nominal duration of the gated frame when Cardiac Framing Type (0018,1064) is equal to​ PCNT.​

C.8.9.4.1.4 Acquisition Date, Acquisition Time​

For PET Images, Acquisition Date (0008,0022) and Acquisition Time (0008,0032) are specified to be Type 2. Acquisition Date​ (0008,0022) and Acquisition Time (0008,0032) use the same time base as Series Time (0008,0031).​

For Series Type (0054,1000) Value 1 equal to STATIC, WHOLE BODY, or DYNAMIC, Acquisition Time (0008,0032) is the real-world​ beginningoftheaccumulationofeventsintothisImage.ForSTATIC,WHOLEBODY,orDYNAMICSeries,AcquisitionTime(0008,0032)​ may vary from Image to Image within a PET Series.​

For Series Type (0054,1000) Value 1 equal to GATED, Acquisition Time (0008,0032) is the real-world beginning of the capability of​ accumulating events into this Image. (The actual accumulation of events has only occurred during an R-R Interval.) For GATED​ Series, Acquisition Time (0008,0032) shall not vary from Image to Image within a PET Series.​

C.8.9.4.1.5 Frame Reference Time​

Frame Reference Time (0054,1300) is the time that the pixel values in the Image occurred. Frame Reference Time is defined as the​ time offset, in msec, from the Series Reference Time, where the Series Reference Time is defined by the combination of Series Date​ (0008,0021) and Series Time (0008,0031).​

Note​

Frame Reference Time (0054,1300) is implementation dependent and may or may not be tied to any real-world event. To​ illustrate the meaning of Frame Reference Time (0054,1300), the following are some examples of possible implementations:​

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•​Example 1: For a long-lived radionuclide and a non-time-varying radiopharmaceutical distribution, an implementation sets​ the Frame Reference Time (0054,1300) to the midpoint of the Actual Frame Duration (0018,1242).​

•​Example2:Forashort-livedradionuclideandanon-time-varyingradiopharmaceuticaldistribution,animplementationsets​ the Frame Reference Time (0054,1300) to the time at which the average activity occurs for a decaying radionuclide, Tave.​ If image acquisition started at the Series Reference Time and the image has not been decay corrected, then Tave will be:​

where:​

•​lambda = decay constant = (ln 2) / T1/2​

•​T1/2 = Radionuclide Half Life (0018,1075)​

•​T = Actual Frame Duration (0018,1242)​

Note that Tave will be sooner than the midpoint of the Actual Frame Duration (0018,1242).​

•​Example 3: For a short-lived radionuclide and a time-varying radiopharmaceutical distribution, an implementation with​ supplementary data (e.g., scanner count rates or blood sample data) sets the Frame Reference Time (0054,1300) to a​ derived time determined to be its best estimate of the time that the pixel values occurred.​

C.8.9.4.1.6 Actual Frame Duration​

The accumulation of counts for a PET Image shall occur entirely between:​

1.​the acquisition starting time (as specified by Acquisition Date (0008,0022) and Acquisition Time (0008,0032)), and​

2.​the acquisition ending time, which is equal to the acquisition starting time in (1) plus the Actual Frame Duration (0018,1242).​

If Series Type (0054,1000) Value 1 is GATED, then the actual accumulation of counts has only occurred during an R-R Interval.​

C.8.9.4.1.7 Secondary Counts Accumulated​

Secondary Counts Accumulated (0054,1311) is multi-valued and, if supplied, has Values corresponding to the Secondary Counts​ Type (0054,1220). The number and order of the Values in Secondary Counts Accumulated (0054,1311) shall be the same as Sec-​ ondary Counts Type (0054,1220).​

C.8.9.4.1.8 Dose Calibration Factor​

The Dose Calibration Factor (0054,1322) is the factor that was used to scale this image from counts/sec to Bq/ml using an external​ dose calibrator. The value shall be one if no dose calibration was applied. The application of a dose calibration correction is specified​ by Corrected Image (0028,0051) equal to DCAL.​

Note​

DoseCalibrationFactor(0054,1322)isnotequaltotheinverseofthesensitivity(kcps/Bq/ml)ofthescanner,whichisusually​ measured for a given radiopharmaceutical distribution and excluding the effects of attenuation.​

C.8.9.4.1.9 Image Index​

Image Index (0054,1330) is an index identifying the position of this image within a PET Series.​

Note​

The scheme for encoding Image Index (0054,1330) is as follows. Images within a PET Series can be viewed as a multi-di-​ mensional array whose possible dimensions include R-R Intervals, Time Slots, Time Slices, and Slices. The dimensions of​ the array are defined by Series Type (0054,1000) Value 1. Each dimension of the array has an index that identifies the pos-​ itionofthisimageinthearray.Theindicesare:R-RIntervalIndex,TimeSlotIndex,TimeSliceIndex,SliceIndex.Theindices​ are calculated as follows:​

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