C.8.9 PET Information Module Definitions

This Section describes Positron Emission Tomography series and image Modules. These Modules contain Attributes that are specific to Positron Emission Tomography images.

C.8.9.1 PET Series Module

Table C.8-60 contains IOD Attributes that describe a PET Series.

Table C.8-60 - PET SERIES MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Series Date (0008,0021) 1 Date the Series started. See C.8.9.1.1.2 for specialization.
Series Time (0008,0031) 1 Time the Series started. See C.8.9.1.1.2 for specialization.
Units (0054,1001) 1 Pixel value units. See C.8.9.1.1.3 for explanation. Defined terms: CNTS, NONE, CM2, CM2ML, PCNT, CPS, BQML, MGMINML, UMOLMINML, MLMING, MLG, 1CM, UMOLML, PROPCNTS, PROPCPS, MLMINML, MLML, GML, STDDEV
SUV Type (0054,1006) 3 Type of Standardized Uptake Value (SUV). Enumerated Values: BSA – body surface area BW – body weight LBM – lean body mass If absent, and the Units (0054,1001) are GML, then the type of SUV shall be assumed to be BW. Note: The type of SUV cannot reliably be deduced from the units alone, i.e. SUVbw and SUVlbm both have units of GML.
Counts Source (0054,1002) 1 The primary source of counts. The primary source leads to the underlying image Units (0054,1001), as opposed to secondary sources which are used during reconstruction correction. Enumerated Values: EMISSION TRANSMISSION
Series Type (0054,1000) 1 A multi-valued indicator of the type of Series. See C.8.9.1.1.4 for explanation. Value 1 Enumerated Values: STATIC DYNAMIC GATED WHOLE BODY Value 2 Enumerated Values: IMAGE REPROJECTION
Reprojection Method (0054,1004) 2C Method for projecting volumetric data onto planar projection. Required if Series Type (0054,1000), Value 2 is REPROJECTION. Defined terms: SUM MAX PIXEL
Number of R-R Intervals (0054,0061) 1C The maximum number of R-R Intervals that may exist in this Series. Required if Series Type (0054,1000), Value 1 is GATED.
Number of Time Slots (0054,0071) 1C The maximum number of Time Slots that may exist in this Series. Required if Series Type (0054,1000), Value 1 is GATED.
Number of Time Slices (0054,0101) 1C The maximum number of Time Slices that may exist in this Series. Required if Series Type (0054,1000), Value 1 is DYNAMIC.
Number of Slices (0054,0081) 1 The maximum number of Slices that may exist in this Series.
Corrected Image (0028,0051) 2 One or more values that indicate which, if any, corrections have been applied to the images in this series. Defined terms: DECY=decay corrected ATTN=attenuation corrected SCAT=scatter corrected DTIM=dead time corrected MOTN=gantry motion corrected (e.g. wobble, clamshell) PMOT=patient motion corrected CLN=count loss normalization (correction for count loss in gated Time Slots). RAN=randoms corrected RADL=non-uniform radial sampling corrected DCAL=sensitivity calibrated using dose calibrator NORM=detector normalization
Randoms Correction Method (0054,1100) 3 Type of randoms correction processing. Defined terms: NONE = no randoms correction DLYD = delayed event subtraction SING = singles estimation
Attenuation Correction Method (0054,1101) 3 A textual description of the attenuation correction processing. e.g. measured vs. calculated, transmission source type (ring, line, point), assumed patient geometry (polygon, ellipse, segmented, attenuation coefficient, skull thickness), post-injection transmission, smoothing.
Scatter Correction Method (0054,1105) 3 A textual description of the scatter correction processing. e.g. convolution-subtraction, dual energy window, model-based, use of attenuation data.
Decay Correction (0054,1102) 1 The real-world event to which images in this Series were decay corrected. See C.8.9.1.1.5 for explanation. Defined terms: NONE = no decay correction START= acquisition start time ADMIN = radiopharmaceutical administration time
Reconstruction Diameter (0018,1100) 3 Diameter, in mm, of the region within which the data was used in creating the reconstruction of the image. Data may exist outside this region and portions of the patient may exist outside this region.
Convolution Kernel (0018,1210) 3 Textual description of the convolution kernel(s) used to reconstruct the data (e.g. name, cutoff, radial/axial/angular, mathematical form, DC handling)
Reconstruction Method (0054,1103) 3 Textual description of reconstruction processing, e.g. 2D filtered backprojection, 2D iterative, 3D PROMIS, 3D FAVOR, 3D iterative.
Detector Lines of Response Used (0054,1104) 3 Textual description of which detector lines of response were used, mashed, or otherwise processed during tomographic reconstruction.
Acquisition Start Condition (0018,0073) 3 Description of how the data collection was started. Defined terms: DENS = density (counts/sec) RDD = relative density difference (change in counts/sec) MANU = manual TIME = time AUTO = automatic, when ready TRIG = physiological trigger See C.8.9.1.1.6 for explanation.
Acquisition Start Condition Data (0018,0074) 3 Count density, change in count density, or physiological triggers causing data collection to start.
Acquisition Termination Condition (0018,0071) 3 Description of how the data collection for the series was stopped. Defined terms: CNTS = counts DENS = density (counts/sec) RDD = relative density difference (change in counts/sec) MANU = manual OVFL = data overflow TIME = time TRIG = physiological trigger See C.8.4.9.1.3 for explanation.
Acquisition Termination Condition Data (0018,0075) 3 Number of counts, count density, change in count density, or physiological triggers causing the termination.
Field of View Shape (0018,1147) 3 Shape of the field of view of the PET camera. Defined Terms: CYLINDRICAL RING HEXAGONAL MULTIPLE PLANAR
Field of View Dimensions (0018,1149) 3 Dimensions of the field of view, in mm. Transverse detector diameter followed by axial width.
Gantry/Detector Tilt (0018,1120) 3 Angle of tilt in degrees of the gantry. See C.8.9.1.1.7 for explanation.
Gantry/Detector Slew (0018,1121) 3 Angle of slew in degrees of the gantry. Positive slew is moving the gantry on the patient’s left toward the patient’s superior, when the patient is supine.
Type of Detector Motion (0054,0202) 3 Describes the detector motion during acquisition. Defined Terms: NONE = stationary gantry STEP AND SHOOT = Interrupted motion, acquire only while stationary CONTINUOUS = Gantry motion and acquisition are simultaneous and continuous WOBBLE = wobble motion CLAMSHELL = clamshell motion
Collimator Type (0018,1181) 2 Collimator Type. Defined Terms: NONE = no collimator RING = transverse septa
Collimator/Grid Name (0018,1180) 3 Label describing the collimator used.
Axial Acceptance (0054,1200) 3 Maximum axial angle accepted, in degrees.
Axial Mash (0054,1201) 3 Number of adjacent axial lines of response mashed together. See C.8.9.1.1.8 for explanation.
Transverse Mash (0054,1202) 3 Number of adjacent transverse lines of response mashed together. See C.8.9.1.1.9 for explanation.
Detector Element Size (0054,1203) 3 Size of an individual detector element, in mm. Transverse dimension followed by axial dimension. For a discrete crystal, this is the crystal size. For a continuous detector, this is the pixel bin size.
Coincidence Window Width (0054,1210) 3 The width of the coincidence timing window, in nsec. The maximum time difference accepted between two single events.
Energy Window Range Sequence (0054,0013) 3 Sequence of Items that describes the energy windows used for this Series. One or more Items are permitted in this sequence. See C.8.9.1.1.10 for explanation.
>Energy Window Lower Limit (0054,0014) 3 The lower limit of the energy window, in KeV.
>Energy Window Upper Limit (0054,0015) 3 The upper limit of the energy window, in KeV.
Secondary Counts Type (0054,1220) 3 Array defining the type of additional counts accumulated during acquisition. Defined terms: DLYD=delayed events SCAT=scattered events in secondary window SING=singles DTIM=events lost due to deadtime

C.8.9.1.1 PET Series Attribute Descriptions

Note: The meaning of a General Series in DICOM is determined by the attributes in the General Series Module and by the Source Entities (Patient, Study, Frame of Reference, Equipment) that originate the Series. The Source Entities are the single-valued entities of the 1->n relationship, where the Series is the multi-valued entity. Therefore, a Series is a group of images that: are from the same patient and study; are from the same Equipment; and, are from the same spatial Frame of Reference.

The PET Image IOD further refines a PET Series IE by the attributes in the PET Series Module, the PET Isotope Module, the PET Multi-gated Acquisition Module and the Acquisition Context Module. These are the attributes that shall not change from Image to Image. Therefore, in addition to the criteria above for a General Series (same patient, study, frame of reference, equipment), the attributes in the PET Series IE define a PET series as a group of images that: are from the same temporal frame of reference; have the same fundamental meaning (e.g. same units: either activity density, metabolism, or attenuation); are derived from the same activity source (emission or transmission); are from the same isotope and radiopharmaceutical; were derived from the same reconstruction processing; and, originated from the same acquisition setup and parameters, including the patient conditions (cardiac stress or rest) if applicable.

C.8.9.1.1.1 Specialization of Image Plane Module and Image Pixel Module Attributes

For PET Series, the following Image Pixel Module attributes shall not vary from Image to Image :

Photometric Interpretation (0028,0004) Rows (0028,0010) Columns (0028,0011) Bits Allocated (0028,0100) Bits Stored (0028,0101) Pixel Representation (0028,0103)

For PET Series, the following Image Plane Module attributes shall not vary from Image to Image :

Pixel Spacing (0028,0030)

For PET Series where Series Type (0054,1000), Value 2 is IMAGE, the following Image Plane Module attributes shall not vary from Image to Image :

Image Orientation (Patient) (0020,0037)

Note: This means that for a Series Type (0054,1000) Value 2 of IMAGE, all images in the PET Series lie on parallel planes. The images, however, may have non-uniform spacing along the normals to the planes.

For PET Series where Series Type (0054,1000), Value 2 is REPROJECTION, the Image Orientation (0020,0037) attribute shall vary such that the images rotate about a single axis. Geometrically, the normal to each image plane is defined by the cross product of its row and column vectors. Each reprojection image has one Center Normal that passes through the center of the image. Reprojection images within a PET Series shall have their Center Normals be co-planar and pass through a single point.

C.8.9.1.1.2 Series Date, Series Time

For PET Series, Series Date (0008,0021) and Series Time (0008,0031) are specified to be Type 1. The Series Date (0008,0021) and Series Time (0008,0031) are used as the reference time for all PET Image attributes that are temporally related, including activity measurements. The Series Date (0008,0021) and Series Time (0008,0031) are not tied to any real-world event (e.g. acquisition start, radiopharmaceutical administration) and their real-world meaning are implementation dependent.

C.8.9.1.1.3 Units

The units of the pixel values obtained after conversion from the stored pixel values (SV) (Pixel Data (7FE0,0010)) to pixel value units (U), as defined by Rescale Intercept (0028,1052) and Rescale Slope (0028,1053). Defined Terms:

CNTS = counts NONE = unitless CM2 = centimeter**2 PCNT = percent CPS = counts/second BQML = Becquerels/milliliter MGMINML = milligram/minute/milliliter UMOLMINML = micromole/minute/milliliter MLMING = milliliter/minute/gram MLG = milliliter/gram 1CM = 1/centimeter UMOLML = micromole/milliliter PROPCNTS = proportional to counts PROPCPS = proportional to counts/sec MLMINML = milliliter/minute/milliliter MLML = milliliter/milliliter GML = grams/milliliter STDDEV = standard deviations

C.8.9.1.1.4 Series Type

The Series Type (0054,1000), Value 1 is used to identify the spatial location and temporal nature of the images within a PET Series. The Enumerated Values and their definitions are:

STATIC = a group of images at varying spatial locations at the same time DYNAMIC = a group of images at a set of spatial locations (e.g. slices) at varying time slices, with all spatial locations acquired at all time slices GATED = a group of images at the same spatial location, same starting and ending time, but acquired in different time slots of (possibly) different R-R intervals WHOLE BODY = same as STATIC, except covering multiple transverse fields of view (and therefore acquired at a different time).

Notes: 1. Using this definition and the comments in C.8.9.1.1.1, here are some examples of PET series and the encoding of Series Type (0054,1000) Value 1.

Static acquisition: a group of n transverse images at varying superior<->inferior locations, all acquired between the same starting and ending time. Series Type = STATIC.

Dynamic acquisition: a group of n*m transverse images at n superior<->inferior locations, acquired with m different starting and ending times. Series Type = DYNAMIC.

Gated acquisition: a group of n*m*p transverse images at n superior<->inferior locations, all acquired between the same starting and ending time, acquired in m different R-R Intervals (as determined by Low R-R Value (0018,1081) and High R-R Value (0018,1082)), and acquired in p time slots of a given R-R Interval (as determined by Trigger Time (0054,1000) ). Series Type = GATED.

Whole body acquisition: a group of n transverse images at varying superior<->inferior locations covering a significant fraction of the entire body. Series Type = WHOLE BODY.

Multiple transverse fields of view: a group of n transverse images at varying superior<->inferior locations. Series Type = WHOLE BODY.

Interleaved: group of 2*n transverse images acquired at overlapped AFOVs to increase transverse sampling. Series Type = WHOLE BODY.

Sagittal (Coronal, Oblique): sagittal (coronal, oblique) re-sliced images derived by reformatting transverse images. The Series Type is STATIC, DYNAMIC, GATED, or WHOLE BODY depending on source Series Type.

Arithmetic: images derived by an arithmetic operation on operand images. The Series Type is STATIC, DYNAMIC, GATED, or WHOLE BODY depending on source Series Type.

Metabolic: images derived by a metabolic model. The Series Type is STATIC, DYNAMIC, GATED, or WHOLE BODY depending on source Series Type.

2. Using this definition, here are some images that are not stored in the same PET Series:

Two images from the same scan that were reconstructed differently.

Emission and transmission images for the same Patient and Study, even if acquired simultaneously (because emission and transmission images have different reconstruction processing).

Two images of same patient, one after NH3 injection and one after FDG injection.

Two images: an original image created from reconstructed scan data and its derived image based on a metabolic model.

The Series Type (0054,1000), Value 2 is used to identify the volumetric meaning of the images within a PET Series. The Enumerated Values and their definitions are:

IMAGE = a tomographic image slice

REPROJECTION = a projection image derived from forward projection through slices of tomographic images, using the algorithm defined in Reprojection Method (0054,1004).

C.8.9.1.1.5 Decay Correction

The Decay Correction (0054,1102) is the real-world event to which images in this Series were decay corrected. If decay correction is applied, all images in the Series shall be decay corrected to the same time. The Defined Terms and definitions are:

NONE = no decay correction START= acquisition start time, Acquisition Time (0008,0032) ADMIN = radiopharmaceutical administration time, Radiopharmaceutical Start Time (0018,1072)

The time to which images have been decay corrected can be derived from Decay Factor (0054,1321), Frame Reference Time (0054,1300), Radionuclide Half Life (0018,1075), Series Date (0008,0021), and Series Time (0008,0031).

C.8.9.1.1.6 Acquisition Start Condition

Acquisition Start Condition (0018,0073) is the method of starting acquisition data collection. The Defined Terms and definitions are:

DENS = preset count density (counts/sec) was reached RDD = preset relative count density difference (change in counts/sec) was reached MANU = acquisition was started manually TIME = preset time limit was reached AUTO = start automatically, when ready TRIG = preset number of physiological triggers was reached

C.8.9.1.1.7 Gantry/Detector Tilt

Gantry/Detector Tilt (0018,1120) for PET Image data is the angle in degrees of the gantry relative to the patient’s major (Head to Feet) axis (or the table supporting the patient). Positive tilt is moving the top of the gantry towards the patient’s feet.

C.8.9.1.1.8 Axial Mash

Axial Mash (0054,1201) is multi-valued and is defined as the number of unique axial Lines of Response (LOR) that were mashed together (center of the axial field of view only). Value 1 is the number of LORs mashed for an odd slice. Value 2 is the number of LORs mashed for an even slice. For discrete crystal scanners, each unique LOR corresponds to a pair of crystals. For continuous detectors whose bin size is variable, the number of LORs mashed is determined by the actual bin size divided by the Detector Element Size (0054,1203), Value 2. The value of Axial Mash (0054,1201) is the same regardless of whether the mashing was done during acquisition or reconstruction.

Note: As an example on a discrete crystal scanner, if a ring difference of -2,0,+2 are binned as an odd slice and a ring difference of -1,+1 are binned as an even slice, then the Axial Mash (0054,1201) is equal to 3\2 .

C.8.9.1.1.9 Transverse Mash

Transverse Mash (0054,1202) is defined as the number of unique transverse Lines of Response (LOR) that were mashed together. For discrete crystal scanners, each unique LOR corresponds to a pair of crystals. For continuous detectors whose bin size is variable, the number of LORs mashed is determined by the actual bin size divided by the Detector Element Size (0054,1203), Value 1. The value of Transverse Mash (0054,1202) is the same regardless of whether the mashing was done during acquisition or reconstruction.

C.8.9.1.1.10 Energy Window Range Sequence

Multiple energy windows are allowed in order to allow coincidence events based on additional Energy Windows (e.g. Compton events scattered in the detector). All energy windows are assumed to contribute to all images in the PET Series.

C.8.9.1.1.11 Temporal Relationships of Images in PET Series

The following diagram shows the temporal relationships of images within a PET Series.

[pic]

C.8.9.2 PET Isotope Module

Table C.8-61 contains IOD Attributes that describe a PET Isotope.

Table C.8-61 - PET ISOTOPE MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Radiopharmaceutical Information Sequence (0054,0016) 2 Sequence of Items that describe isotope information. Zero or more Items shall be included in this sequence.
>Radionuclide Code Sequence (0054,0300) 2 Sequence that identifies the radionuclide. Zero or one item shall be included in this sequence.
>>Include ‘Code Sequence Macro’ Table 8.8-1 Baseline CID 4020 .
>Radiopharmaceutical Route (0018,1070) 3 Route of administration.
>Administration Route Code Sequence (0054,0302) 3 Sequence that identifies the administration route of the radiopharmaceutical. Only a single Item is permitted in this sequence.
>>Include ‘Code Sequence Macro’ Table 8.8-1 Baseline CID 11.
>Radiopharmaceutical Volume (0018,1071) 3 Volume of administered radiopharmaceutical in cubic cm.
>Radiopharmaceutical Start Time (0018,1072) 3 Time of start of administration. The actual time of radiopharmaceutical administration to the patient for imaging purposes, using the same time base as Series Time (0008,0031). The use of this Attribute is deprecated in favor of Radiopharmaceutical Start DateTime (0018,1078). Note: The use of a time alone can cause confusion when the procedure spans midnight.
>Radiopharmaceutical Start DateTime (0018,1078) 3 Date and time of start of administration. The actual date and time of radiopharmaceutical administration to the patient for imaging purposes, using the same time base as Series Time (0008,0031).
>Radiopharmaceutical Stop Time (0018,1073) 3 Time of end of administration. The actual ending time of radiopharmaceutical administration to the patient for imaging purposes, using the same time base as Series Time (0008,0031). The use of this Attribute is deprecated in favor of Radiopharmaceutical Stop DateTime (0018,1079). Note: The use of a time alone can cause confusion when the procedure spans midnight.
>Radiopharmaceutical Stop DateTime (0018,1079) 3 Date and time of end of administration. The actual ending date and time of radiopharmaceutical administration to the patient for imaging purposes, using the same time base as Series Time (0008,0031).
>Radionuclide Total Dose (0018,1074) 3 The radiopharmaceutical dose administered to the patient measured in Becquerels (Bq) at the Radiopharmaceutical Start Time (0018,1072). Note: In other IODs, such as the NM IOD, this same attribute is specified in MegaBecquerels (MBq).
>Radionuclide Half Life (0018,1075) 3 The radionuclide half life, in seconds, that was used in the correction of this image.
>Radionuclide Positron Fraction (0018,1076) 3 The radionuclide positron fraction (fraction of decays that are by positron emission) that was used in the correction of this image.
>Radiopharmaceutical Specific Activity (0018,1077) 3 The activity per unit mass of the radiopharmaceutical, in Bq/micromole, at the Radiopharmaceutical Start Time (0018,1072).
>Radiopharmaceutical (0018,0031) 3 Name of the radiopharmaceutical.
>Radiopharmaceutical Code Sequence (0054,0304) 3 Sequence that identifies the radiopharmaceutical. Only a single Item is permitted in this sequence.
>>Include ‘Code Sequence Macro’ Table 8.8-1 Baseline CID 4021 .
Intervention Drug Information Sequence (0018,0026) 3 Sequence of Items that describes the intervention drugs used. One or more items are permitted in this sequence.
>Intervention Drug Name (0018,0034) 3 Name of the intervention drug.
>Intervention Drug Code Sequence (0018,0029) 3 Sequence that identifies the intervention drug name. Only a single Item is permitted in this Sequence.
>>Include ‘Code Sequence Macro’ Table 8.8-1 Baseline CID 10.
>Intervention Drug Start Time (0018,0035) 3 Time of administration of the intervention drug, using the same time base as for the Series Time (0008,0031).
>Intervention Drug Stop Time (0018,0027) 3 Time of completion of administration of the intervention drug, using the same time base as for the Series Time (0008,0031).
>Intervention Drug Dose (0018,0028) 3 Intervention drug dose, in mg.

C.8.9.3 PET Multi-gated Acquisition Module

Table C.8-62 contains IOD Attributes that describe a PET Multi-gated Acquisition.

Table C.8-62 - PET MULTI-GATED ACQUISITION MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Beat Rejection Flag (0018,1080) 2 Heart beat duration sorting has been applied. Enumerated values: Y = yes N = no
Trigger Source or Type (0018,1061) 3 Text indicating trigger source. Defined terms: EKG
PVC Rejection (0018,1085) 3 Description of the type of PVC rejection criteria used.
Skip Beats (0018,1086) 3 Number of beats skipped after a detected arrhythmia.
Heart Rate (0018,1088) 3 Average number of heart beats per minute for the collection period for this image. This shall include all accepted beats as well as rejected beats.
Cardiac Framing Type (0018,1064) 3 Description of type of framing performed. See C.7.6.18.1.1.1 for description and Defined Terms.

C.8.9.4 PET Image Module

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

Table C.8-63 - PET IMAGE MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Image Type (0008,0008) 1 Image identification characteristics. See C.8.9.4.1.1 for specialization.
Samples per Pixel (0028,0002) 1 Number of samples (planes) in this image. This value shall be 1.
Photometric Interpretation (0028,0004) 1 Specifies the intended interpretation of the pixel data. See C.8.9.4.1.2 for specialization.
Bits Allocated (0028,0100) 1 Number of bits allocated for each pixel sample. Each sample shall have the same number of bits allocated. Enumerated values: 16.
Bits Stored (0028,0101) 1 Number of bits stored for each pixel sample. Each sample shall have the same number of bits stored. The value shall be the same as the value in Bits Allocated (0028,0100).
High Bit (0028,0102) 1 Most significant bit for pixel sample data. Each sample shall have the same high bit. Shall be one less than the value in Bits Stored (0028,0101).
Rescale Intercept (0028,1052) 1 The value b in relationship between stored values (SV) and pixel value units (U) defined in Units (0054,1001): U = m*SV+b. The Rescale Intercept is always zero for PET images.
Rescale Slope (0028,1053) 1 m in the equation specified in Rescale Intercept (0028,1052).
Frame Reference Time (0054,1300) 1 The time that the pixel values in the image occurred. Frame Reference Time is the offset, in msec, from the Series reference time. See explanation in C.8.9.4.1.5.
Trigger Time (0018,1060) 1C Time interval, in msec, from the start of the trigger to the beginning of data acquisition for this image. Required if Series Type (0054,1000), Value 1 is GATED.
Frame Time (0018,1063) 1C Nominal duration per individual frame, in msec. Required if Series Type (0054,1000), Value 1 is GATED. See C.8.9.4.1.3 for explanation.
Low R-R Value (0018,1081) 1C R-R interval lower limit for beat rejection, in msec. Required if Series Type (0054,1000), Value 1 is GATED and Beat Rejection Flag (0018,1080) is Y.
High R-R Value (0018,1082) 1C R-R interval upper limit for beat rejection, in msec. Required if Series Type (0054,1000), Value 1 is GATED and Beat Rejection Flag (0018,1080) is Y.
Lossy Image Compression (0028,2110) 1C Specifies whether an Image has undergone lossy compression. Enumerated values: 00 = Image has NOT been subjected to lossy compression. 01 = Image has been subjected to lossy compression. See C.7.6.1.1.5. Required if Lossy Compression has been performed on the image.
Image Index (0054,1330) 1 An index identifying the position of this image within a PET Series. See C.8.9.4.1.9 for explanation.
Acquisition Date (0008,0022) 2 The date the acquisition of data that resulted in this image started. See C.8.9.4.1.4 for specialization.
Acquisition Time (0008,0032) 2 The time the acquisition of data that resulted in this image started. See C.8.9.4.1.4 for specialization.
Actual Frame Duration (0018,1242) 2 Elapsed time of the data acquisition for this image, in msec. See C.8.9.4.1.6 for explanation.
Nominal Interval (0018,1062) 3 Average duration of accepted beats, in msec, of the R-R interval.
Intervals Acquired (0018,1083) 3 Number of heartbeats that fall within Low R-R Value (0018,1081) and High R-R Value (0018,1082), and were therefore accepted and contribute coincidence events to this R-R Interval.
Intervals Rejected (0018,1084) 3 Number of heartbeats that fall outside Low R-R Value (0018,1081) and High R-R Value (0018,1082), and do not contribute coincidence events to this R-R Interval. However, they may contribute coincidence events to other R-R Intervals.
Primary (Prompts) Counts Accumulated (0054,1310) 3 The sum of events that occur in the primary event channel. The counts include Trues +Scatter+ Randoms if Randoms Correction Method (0054,1100) is NONE; otherwise the counts are Trues +Scatter.
Secondary Counts Accumulated (0054,1311) 3 Sum of counts accumulated in secondary channels. See C.8.9.4.1.7 for explanation.
Slice Sensitivity Factor (0054,1320) 3 The slice-to-slice sensitivity correction factor that was used to correct this image. The value shall be one if no slice sensitivity correction was applied.
Decay Factor (0054,1321) 1C The decay factor that was used to scale this image. Required if Decay Correction (0054,1102) is other than NONE. If decay correction is applied, all images in the Series shall be decay corrected to the same time.
Dose Calibration Factor (0054,1322) 3 Factor that was used to scale this image from counts/sec to Bq/ml using a dose calibrator. The value shall be one if no dose calibration was applied. See C.8.9.4.1.8 for explanation.
Scatter Fraction Factor (0054,1323) 3 An estimate of the fraction of acquired counts that were due to scatter and were corrected in this image. The value shall be zero if no scatter correction was applied.
Dead Time Factor (0054,1324) 3 The average dead time correction factor that was applied to this image. The value shall be one if no dead time correction was applied.
Include 'General Anatomy Optional Macro' Table 10-7 No Context ID for the Anatomic Region Sequence is defined.
Slice Progression Direction (0054,0500) 3 Describes the anatomical direction that slices are progressing as the slices are considered in order (as defined by the Slice Index. See section C.8.9.4.1.9 for a definition of Slice Index). Meaningful only for cardiac images. When View Code Sequence (0054,0220) indicates a short axis view, then Enumerated Values are: APEX_TO_BASE BASE_TO_APEX
View Code Sequence (0054,0220) 3 Sequence that describes the projection of the anatomic region of interest. Only a single Item is permitted in this sequence.
>Include ‘Code Sequence Macro’ Table 8.8-1 Baseline CID 26.
>View Modifier Code Sequence (0054,0222) 2C View Modifier. Required if needed to fully specify the View. Zero or one Item shall be included in this sequence.
>>Include ‘Code Sequence Macro’ Table 8.8-1 Baseline CID 23.

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 PS 3.3 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: For PET images, Image Type (0008,0008) Value 1 will be ORIGINAL for reconstructed images. DERIVED may be appropriate 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

For PET images, Photometric Interpretation (0028,0004) shall have one of the following Enumerated Values:

MONOCHROME2

See C.7.6.3.1.2 for definition of this term.

C.8.9.4.1.3 Frame Time

The 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. The 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, the Acquisition Time (0008,0032) is the real-world beginning of the accumulation of events into this Image. For STATIC, WHOLE BODY, or DYNAMIC Series, the Acquisition Time (0008,0032) may vary from Image to Image within a PET Series.

For Series Type (0054,1000) Value 1 equal to GATED, the 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, the 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:

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).

Example 2: For a short-lived radionuclide and a non-time-varying radiopharmaceutical distribution, an implementation sets 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 the 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 Secondary 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: Dose Calibration Factor (0054,1322) is not equal to the inverse of the sensitivity (kcps/Bq/ml) of the scanner, which is usually 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-dimensional array whose possible dimensions include R-R Intervals, Time Slots, Time Slices, and Slices. The dimensions of the array are defined by the Series Type (0054,1000) Value 1. Each dimension of the array has an index that identifies the position of this image in the array. The indices are: R-R Interval Index, Time Slot Index, Time Slice Index, Slice Index. The indices are calculated as follows:

Index Range of Index Order of Images along that Dimension
R-R Interval Index 1 to Number of R-R Intervals (0054,0061) Increasing Low R-R Value (0018,1081)
Time Slot Index 1 to Number of Time Slots (0054,0071) Increasing Trigger Time (0018,1060)
Time Slice Index 1 to Number of Time Slices (0054,0101) Increasing Frame Reference Time (0054,1300)
Slice Index 1 to Number of Slices (0054,0081) If Series Type (0054,1000) Value 2 is IMAGE: Order is in increasing position along the normal, where the normal is determined by the cross product of the direction cosines of the row and column of the image. See Image Orientation (0020,0037) in the Image Plane Module. If Series Type (0054,1000) Value 2 is REPROJECTION: Order is in increasing or decreasing angle of the normal, where the normal is determined by the cross product of the direction cosines of the row and column of the image. See Image Orientation (0020,0037) in the Image Plane Module. (Note that reprojection images rotate about only a single axis as described in C.8.9.1.1.1. Therefore, all normals are co-planar and make a single angle with respect to each other.)

Using these index values the position of this image within the multi-dimensional array (the Image Index (0054,1330)) is calculated as follows:

Series Type (0054,1000), Value 1 Dimensions of Array (Last dimension is most rapidly changing) Encoding of Image Index (0054,1330)
STATIC Slice Slice Index
WHOLE BODY Slice Slice Index
DYNAMIC Time Slice \ Slice ( ( Time Slice Index - 1 ) * ( Number of Slices (0054,0081) ) ) + Slice Index
GATED R-R Interval \ Time Slot \ Slice ( ( R-R Interval Index - 1 ) * ( Number of Time Slots (0054,0071) ) * ( Number of Slices (0054,0081) ) ) + ( ( Time Slot Index - 1 ) * ( Number of Slices (0054,0081) ) ) + Slice Index

C.8.9.5 PET Curve Module

Retired. See PS 3.3 2004.