Number of Detectors (0054,0021) is the number of separate detectors which differentiate the frames in this image. When Image Type (0008,0008), Value 3, is RECON TOMO or RECON GATED TOMO, then the Number of Detectors (0054,0021) shall be 1.
Note: Number of Detectors (0054,0021) does not necessarily represent the actual number of detectors used during data acquisition.
Example 1: In a TOMO acquisition in which frames from 2 or more detectors are interleaved to form one continuous set of frames, then no distinction is made between frames on the basis of which detector created them. In this case, the Number of Detectors (0054,0021) would be 1.
Example 2: In a WHOLE BODY acquisition in which a single detector acquires anterior and posterior views in two separate passes, the Number of Detectors (0054,0021) would be 2.
Detector Vector (0054,0020) is an indexing vector. The value of the nth element of this vector is the detector number of the nth frame in this image, and shall have a value from 1 to Number of Detectors (0054,0021).