DICOM Standard Browser

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Data synced with official DICOM standard on 4 December 2019. The DICOM Standard is under continuous maintenance, and the current official version is available at http://dicom.nema.org/. DICOM Parts 3 and 6, © NEMA. Please note that the most recent PDF version of the standard is the official reference, and should checked when making technical decisions.

Exposure Time in ms Attribute

Tag (0018,9328) Conditionally Required (1C) ExposureTimeInms 1 Double (FD)

Duration of exposure for this frame in milliseconds. If Acquisition Type (0018,9302) equals SPIRAL the duration of the exposure time for this frame shall be Revolution Time (0018,9305) divided by the Spiral Pitch Factor (0018,9311). See Section C.8.15.3.8.1.

Required if Frame Type (0008,9007) Value 1 of this frame is ORIGINAL, or if Image Type (0008,0008) Value 1 is ORIGINAL and Multi-energy CT Acquisition (0018,9361) is YES. May be present otherwise.

Section C.8.15.3.8.1

C.8.15.3.8.1 Exposure Time in ms Attribute (Informative)

An example of how the value of Exposure Time in ms (0018,9328) can be calculated:

The Exposure Time Texposuretime of a volume shall be the time of the X-Ray radiation in position with this volume. It depends on the travel speed and the total collimation width.

Texposuretime of the volume represented by a distinguished frame of a Spiral Scan can be calculated as follows:

Texposuretime = N x S / Vtravelspeed

CTpitchfactor = DD / N x S

Vtravelspeed = DD / Trevolutiontime

From this the exposure time can be derived:

Texposuretime = N x S x Trevolutiontime / DD = Trevolutiontime / CTpitchfactor

Legend:

DD = Table Feed per Rotation (0018,9310) in mm distance moved by the patient support in the z direction per 360° revolution in Spiral scanning

S = collimation of a single slice in mm

N = number slices

N x S = Total Collimation Width (0018,9307) in mm

Vtravelspeed = Table Speed (0018,9309) in mm/second, travel speed of the patient table

Trevolutiontime = Revolution time (0018,9305) in seconds

CTpitchfactor = Spiral Pitch Factor (0018,9311)