C.8.4.13 NM Multi-gated Acquisition Module

C.8.4.13 NM Multi-gated Acquisition Module (Current)
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Table C.8-13 specifies the Attributes of the NM Multi-gated Acquisition Module, which describe a multi-gated acquisition image performed on the patient. This refers to frames acquired while the patient is connected to a gating device.

Table C.8-13. NM Multi-Gated Acquisition Module Attributes

Attribute Name	Tag	Type	Attribute Description
Beat Rejection Flag	(0018,1080)	3	Heart beat duration sorting has been applied. Enumerated Values: Y yes N no
PVC Rejection	(0018,1085)	3	Description of type of arrhythmic beat 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 these frames. This shall include all accepted beats as well as rejected beats.
Gated Information Sequence	(0054,0062)	2C	Sequence of Items that describe R-R intervals. Each gated interval is defined by an upper and lower range of heart beat durations. Required if the Frame Increment Pointer (0028,0009) contains the Tag for R-R Interval Vector (0054,0060). Zero or more Items shall be included in this Sequence. The number of Items shall be equal to Number of R-R Intervals (0054,0061). The first Item corresponds to frames with value of 1 in the R-R Interval Vector (0054,0060), the second Item with value 2, etc.
>Trigger Time	(0018,1060)	3	Time interval measured in msec from the start of the R-wave to the beginning of the data taking.
>Cardiac Framing Type	(0018,1064)	3	Description of type of framing performed. See Section C.7.6.18.1.1.1 for description and Defined Terms.
>Data Information Sequence	(0054,0063)	2	Sequence of Items that describe gating criteria. Zero or more Items shall be included in this Sequence. See Section C.8.4.13.1.1.
>>Frame Time	(0018,1063)	1	Nominal time per individual frame in msec.
>>Nominal Interval	(0018,1062)	3	Average duration of accepted beats, in msec.
>>Low R-R Value	(0018,1081)	3	R-R interval lower limit for beat rejection, in msec.
>>High R-R Value	(0018,1082)	3	R-R interval upper limit for beat rejection, in msec.
>>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 gamma events to this R-R Interval.
>>Intervals Rejected	(0018,1084)	3	Number of heartbeats that fall outside Low R-R (0018,1081) and High R-R Value (0018,1082), and do not contribute gamma events to this R-R Interval. However, they may contribute gamma events to other R-R Intervals.
>>Time Slot Information Sequence	(0054,0072)	2C	Sequence of Items that describe Time Slot Information. Required if the Frame Increment Pointer (0028,0009) contains the Tag for Time Slot Vector (0054,0070). Zero or more Items shall be included in this Sequence. The number of Items shall be equal to Number of Time Slots (0054,0071). The first Item corresponds to frames with value of 1 in the Time Slot Vector (0054,0070), the second Item with value 2, etc.
>>>Time Slot Time	(0054,0073)	3	The total amount of time, in msec, that the acquisition accumulates gamma events into this frame. See Section C.8.4.13.1.2.

C.8.4.13.1 NM Multi-gated Acquisition Module Attribute Descriptions

C.8.4.13.1.1 Data Information Sequence

Data Information Sequence (0054,0063) shall contain a single Item that applies to the sum of all angular views, except when Image Type (0008,0008) Value 3 is GATED TOMO. In this case it shall have either a single Item that applies to the sum of all angular views, or it shall have one Item for each angular view.

C.8.4.13.1.2 Time Slot Time

The Time Slot Time (0054,0073) records the effective imaging time of each Time Slot. For example, if some of the accepted beats are shorter than others then the last frames may not receive a contribution from the shorter beats. The Time Slot Time for a Time Slot is the total acquisition time for that Time Slot. It is approximately equal to Frame Time (0018,1063) multiplied by the number of accepted beats contributing to the Time Slot.

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