C.8.22.5 Enhanced PET Image Functional Group Macros

The following sections contain Functional Group macros specific to the Enhanced PET Image IOD.

Note: The attribute descriptions in the Functional Group Macros are written as if they were applicable to a single frame (i.e., the macro is part of the Per-frame Functional Groups Sequence). If an attribute is applicable to all frames (i.e. the macro is part of the Shared Functional Groups Sequence) the phrase “this frame” in the attribute description shall be interpreted to mean “ for all frames”.

C.8.22.5.1 PET Frame Type Macro

Table C.8.22-10 specifies the attributes of the PET Frame Type Functional Group macro.

Table C.8.22-10PET FRAME TYPE MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
PET Frame Type Sequence (0018,9751) 1 A sequence that describes general characteristics of this frame. Only a single Item shall be included in this sequence.
>Frame Type (0008,9007) 1 Type of Frame. A multi-valued attribute analogous to the Image Type (0008,0008). Enumerated Values and Defined Terms are the same as those for the four values of the Image Type (0008,0008) attribute, except that the value MIXED is not allowed. See C.8.16.1 and C.8.22.3.1.
>Include ‘Common CT/MR Image Description Macro' Table C.8-131

C.8.22.5.2 PET Frame Acquisition Macro

Table C.8.22-11 specifies the attributes of the PET Frame Acquisition Functional Group macro.

Table C.8.22-11PET FRAME ACQUISITION MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
PET Frame Acquisition Sequence (0018,9732) 1 Contains the attributes defining the PET acquisition mode. Only a single Item shall be included in this sequence.
>Table Height (0018,1130) 1 The distance in mm from the top of the patient table to the data collection center . The distance is positive when the table is below the data collection center.
>Gantry/Detector Tilt (0018,1120) 1 Nominal angle of tilt in degrees of the scanning gantry. Not intended for mathematical computations. Zero degrees means the gantry is not tilted, negative degrees are when the top of the gantry is tilted away from where the table enters the gantry.
>Gantry/Detector Slew (0018,1121) 1 Nominal angle of slew in degrees of the gantry. Not intended for mathematical computations. Zero degrees means the gantry is no slewed. Positive slew is moving the gantry on the patient’s left toward the patient’s superior, when the patient is supine.
>Data Collection Diameter (0018,0090) 1 The diameter in mm of the region over which data were collected. See C.8.22.5.4.1.

C.8.22.5.3 PET Detector Motion Details Macro

Table C.8.22-12 specifies the attributes of the PET Detector Motion Details Functional Group macro.

Table C.8.22-12PET DETECTOR MOTION DETAILS MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
PET Detector Motion Details Sequence (0018,9733) 1 Contains the attributes defining the details of the motion of the Detector. Only a single Item shall be included in this sequence.
>Rotation Direction (0018,1140) 1 Direction of rotation of the detector about the gantry, as viewed while facing the gantry where the table enters the gantry. Enumerated Values: CW = clockwise CC = counter clockwise
>Revolution Time (0018,9305) 1 The time in seconds of a complete revolution of the detector around the gantry orbit.

C.8.22.5.4 PET Position Macro

Table C.8.22-14 specifies the attributes of the PET Position Functional Group macro.

Table C.8.22-14PET POSITION MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
PET Position Sequence (0018,9735) 1 Contains the attributes defining the PET geometry. Only a single Item shall be included in this sequence.
>Table Position (0018,9327) 1C Relative longitudinal position of acquisition location of this frame in mm from an implementation specific reference point. Shall be relative to the same reference point for all frames in this SOP Instance, but may be different from the reference point in other SOP Instances. Positions as the table moves into the gantry viewed from the front are more negative. Notes: 1. For contiguous slices reconstructed from multiple detectors one would expect different values for adjacent slices. 2. Lateral positioning or tilting or swiveling are not described. Required if Frame Type (0008,9007) Value 1 of this frame is ORIGINAL. May be present otherwise.
>Data Collection Center (Patient) (0018,9313) 1C The x, y, and z coordinates (in the patient coordinate system) in mm of the center of the region in which data were collected. See C.8.22.5.4.1. Required if Frame Type (0008,9007) Value 1 equals ORIGINAL. May be present otherwise.
>Reconstruction Target Center (Patient) (0018,9318) 1C The x, y, and z coordinates (in the patient coordinate system) of the reconstruction center target point as used for reconstruction in mm. See C.8.22.5.4.1. Note: If the reconstructed image is not magnified or panned the value corresponds with the Data Collection Center (0018,9313) attribute. Required if Frame Type (0008,9007) Value 1 equals ORIGINAL. May be present otherwise.

C.8.22.5.4.1 Relationships Between PET Geometric Attributes (Informative)

In Figure C.8.22-1 the relationship of the Geometric Attributes within the PET Geometry and PET Reconstruction functional groups is shown. The figure, viewed from the front of the gantry (where the table enters the gantry), is informative only and is not meant to represent a standardization of an equipment-based frame of reference.

[pic]

Figure C.8.22-1: Geometry of PET Acquisition System

C.8.22.5.5 PET Frame Correction Factors Macro

Table C.8.22-15 specifies the attributes of the PET Frame Correction Factors Functional Group macro.

Table C.8.22-15PET FRAME CORRECTION FACTORS MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
PET Frame Correction Factors Sequence (0018,9736) 1 Contains the attributes that describe the correction factors applied to this frame. Only a single Item shall be included in this sequence.
>Primary (Prompts) Counts Accumulated (0054,1310) 1C The sum of events that occur in the primary event channel. The counts include Trues +Scatter+ Randoms if Corrected Image (0028,0051) includes RAN; otherwise the counts are Trues +Scatter. Required if Frame Type (0008,9007) Value 1 is ORIGINAL. May be present otherwise.
>Slice Sensitivity Factor (0054,1320) 1C The slice-to-slice sensitivity correction factor that was used to correct this frame. The value shall be one if no slice sensitivity correction was applied. Required if Frame Type (0008,9007) Value 1 is ORIGINAL. May be present otherwise.
>Decay Factor (0054,1321) 1C The decay factor that was used to scale this frame. Required if Decay Corrected (0018,9758) equals YES.
>Scatter Fraction Factor (0054,1323) 1C An estimate of the fraction of acquired counts that were due to scatter and that were corrected in this frame. The value shall be zero if no scatter correction was applied. Required if Frame Type (0008,9007 Value 1 is ORIGINAL. May be present otherwise.
>Dead Time Factor (0054,1324) 1C The average dead time correction factor that was applied to this frame. The value shall be one if no dead time correction was applied. Required if Frame Type (0008,9007) Value 1 is ORIGINAL. May be present otherwise.

C.8.22.5.6 PET Reconstruction Macro

Table C.8.22-17 specifies the attributes of the PET Reconstruction Functional Group Macro, which describe the method used to reconstruct this image.

Table C.8.22-17PET RECONSTRUCTION MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
PET Reconstruction Sequence (0018,9749) 1 Contains the attributes describing the reconstruction process for this frame. Only a single Item shall be included in this sequence.
>Reconstruction Type (0018,9756) 1C Description of the type of algorithm used when reconstructing the image from the data acquired during the acquisition process. Defined Terms: 2D 3D 3D_REBINNED Required if Frame Type (0008,9007) Value 1 equals ORIGINAL. May be present otherwise.
>Reconstruction Algorithm (0018,9315) 1C Description of the algorithm used when reconstructing the image from the data acquired during the acquisition process. Defined Terms: FILTER_BACK_PROJ REPROJECTION RAMLA MLEM Required if Frame Type (0008,9007) Value 1 of this frame is ORIGINAL. May be present otherwise.
>Iterative Reconstruction Method (0018,9769) 1 Iterative Reconstruction Method used. Enumerated Values: YES NO
>Number of Iterations (0018,9739) 1C Number of iterations. Required if Frame Type (0008,9007) Value 1 equals ORIGINAL and Iterative Reconstruction Method (0018,9769) equals YES. May be present otherwise.
>Number of Subsets (0018,9740) 1C Number of subsets. Required if Frame Type (0008,9007)) Value 1 equals ORIGINAL and Iterative Reconstruction Method (0018,9769) equals YES. May be present otherwise.
>Reconstruction Diameter (0018,1100) 1C The diameter in mm of the region from which data were used in creating the reconstruction of the image. Data may exist outside this region and portions of the patient may exist outside this region. See C.8.22.5.4.1. Required if Frame Type (0008,9007) Value 1 equals ORIGINAL and Reconstruction Field of View (0018,9317) is not present. Otherwise may be present if Frame Type (0008,9007) Value 1 equals DERIVED and Reconstruction Field of View (0018,9317) is not present.
>Reconstruction Field of View (0018,9317) 1C The field of view width (x-dimension) followed by height (y-dimension) as used for reconstruction in mm. Required if Image Type (0008,9007) Value 1 equals ORIGINAL and Reconstruction Diameter (0018,1100) is not present. Otherwise may be present if Frame Type (0008,9007) Value 1 equals DERIVED and Reconstruction Diameter (0018,1100) is not present.

C.8.22.5.7 PET Table Dynamics Macro

Table C.8.22-18 specifies the attributes of the PET Table Dynamics Functional Group Macro, which describes the table motion during acquisition of the data.

Table C.8.22-18PET TABLE DYNAMICS MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
PET Table Dynamics Sequence (0018,9734) 1 Contains the attributes describing the movement of the PET Table. Only a single Item shall be included in this sequence.
>Table Speed (0018,9309) 1 The distance in mm that the Table moves in one second during the gathering of data that resulted in this frame.