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Support was added for gated (SPECT) studies, with attention to conversion between InterFile and DICOM. The usage of Gated SPECT in InterFile 3.3 was based on a referenced proposal. The following tables show useful relations between DICOM tags, InterFile keys and other terminology. Internally we preserve InterFile related keys, because they seem less prone to interpretation differences.

DICOM
"Image Type" (0x0008;0x0008)
InterFile
"type of data :="
GATED <--> GATED
GATED SPECT <--> GSPECT (unreconstructed)
RECON GATED SPECT <--> GSPECT (reconstructed)

Table 1.: Relation of gated acquisition types between DICOM and InterFile

InterFile: alias = key DICOM calculated units
N = total number of images Heart Rate (0x0018;0x1088) = (Cobs / S) * 60 * 1000 [bpm]
S = study duration (acquired) sec Actual Frame Duration (0x0018;0x1242) = T * 1000 [ms]
I = image duration (sec) Frame Time (0x0018;0x1063) = I * 1000 [ms]
P = number of projections Time Slot Time (0x0054;0x0073) = ((Cacq * I) / N) * 1000 [ms]
T = time per projection (sec) Number of Frames in Rotation (0x0054,0x0053) = P -
Cacq = cardiac cycles acquired Intervals Acquired (0x0018;0x1083) = Cacq

or divided by P repeated tags

-
Cobs = cardiac cycles observed Intervals Rejected (0x0018;0x1084) = (Cobs - Cacq)

or divided by P repeated tags

-
Astart = start angle Start Angle (0x0054,0x0200) = (180 - Astart + 360) % 360 [degrees]

Table 2.: Mapping of gated (SPECT) between InterFile keys and DICOM tags

Important key relations for InterFile:

  • "% R-R cycles acquired this window" = (Cacq/Cobs) * 100
  • "time per projection (sec)" = T = (S/P)

Dimensions in DICOM mapped to (X)MedCon (= InterFile):

 GATEDGATED TOMORECON GATED TOMO
dim[7] =energy windowsenergy windows-
dim[6] =detector headsdetector heads-
--(rotations = 1)-
dim[5] =R-R intervalsR-R intervalsR-R intervals
dim[4] =-time slotstime slots
dim[3] =time slotsangular viewsslices

Table 3.: DICOM dimensions mapped in (X)MedCon

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Page last modified on January 05, 2008, at 09:29 PM