C.8.15.3.2 CT Acquisition Type Macro

Table C.8-118 specifies the attributes of the CT Acquisition Type Functional Group macro.

Table C.8-118CT ACQUISITION TYPE MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
CT Acquisition Type Sequence (0018,9301) 1 Contains the attributes defining the CT acquisition mode. Only a single Item shall be included in this sequence.
>Acquisition Type (0018,9302) 1C Description of the method used during acquisition of this frame. See C.8.15.3.2.1 for Defined Terms. Required if Frame Type (0008,9007) Value 1 of this frame is ORIGINAL. May be present otherwise.
>Tube Angle (0018,9303) 1C The constant angle at which the x-ray source is located during acquisition. 0 degrees means that the source is located at the highest point of the gantry orbit. Degrees increase from 0 to positive 360 in a clockwise direction as viewed when facing the gantry where the table enters the gantry. Required if Frame Type (0008,9007) Value 1 of this frame is ORIGINAL and Acquisition Type (0018,9302) is CONSTANT_ANGLE. May be present otherwise if Frame Type (0008,9007) Value 1 of this frame is DERIVED and Acquisition Type (0018,9302) is CONSTANT_ANGLE.
>Constant Volume Flag (0018,9333) 1C Identifies that the acquisition was performed by repetitively acquiring the same volume set over a period of time. Note: The Acquisition Type (0018,9302) value may be SEQUENCED, SPIRAL or STATIONARY depending on whether table movement is necessary to cover the volume. Enumerated Values YES NO Required if Frame Type (0008,9007) Value 1 of this frame is ORIGINAL. May be present otherwise.
>Fluoroscopy Flag (0018,9334) 1C Identifies that near real-time display of a block of continuously acquired data was performed, which may result in a lower than usual image quality. Enumerated Values YES NO Required if Frame Type (0008,9007) Value 1 of this frame is ORIGINAL. May be present otherwise.

C.8.15.3.2.1 Acquisition Type

Acquisition Type (0018,9302) has the following Defined Terms:

SEQUENCED identifies that the acquisition was performed by acquiring single or multi detector data while rotating the source about the gantry while the table is not moving. Additional slices are acquired by incrementing the table position and again rotating the source about the gantry while the table is not moving.

SPIRAL identifies that the acquisition was performed by acquiring data while rotating the source about the gantry while continuously moving the table.

CONSTANT_ANGLE identifies that the acquisition was performed by holding the source at a constant angle and moving the table to obtain a projection image (e.g., a localizer image).

STATIONARY identifies that the acquisition was performed by holding the table at a constant position and acquiring multiple slices over time at the same location.

FREE identifies that the acquisition was performed while rotating the source about the gantry while the table movement is under direct control of a human operator or under the control of an analysis application (e.g., fluoroscopic image).