[Insight-users] SPECT origin reading problem

[Bc. Michal Srna]

Hello,

I have SPECT (single photo emission computed tomography) 3D DICOM data set
file with 90 slices inside it. Problem is, that ITK will read origin of
these data as 0x0x0. I think, the proper origin of this data is located in
header in tag "(0020,0032)    Image Position (Patient)", which is not 0x0x0.
Can anyone please help why this is happening?

For example in CT data I have, it reads as origin values correctly the
values located in that tag (0020,0032).

I think, the problem is, that in SPECT data is tag (0020,0032) hidden under
tag "(0054,0022)    Detector Information Sequence" and mayby, ITK can't find
it, because in that CT data, is this tag (0020,0032) normally visible and is
not hidden under another tag.

Here is the example of that part of SPECT header data:

(0054,0022)    Detector Information Sequence                       VR: SQ
Length: 260
    (0018,1120)    Gantry/Detector Tilt                                VR:
DS    Length: 2     Value: 0
    (0018,1145)    Center of Rotation Offset                           VR:
DS    Length: 2     Value: 0
    (0018,1147)    Field of View Shape                                 VR:
CS    Length: 0
    (0018,1149)    Field of View Dimension(s)                          VR:
IS    Length: 4     Value: 0\0
    (0018,1180)    Collimator/grid Name                                VR:
SH    Length: 4     Value: LEHR
    (0018,1181)    Collimator Type                                     VR:
CS    Length: 4     Value: PARA
    (0018,1182)    Focal Distance                                      VR:
IS    Length: 2     Value: 0
    (0018,1183)    X Focus Center                                      VR:
DS    Length: 2     Value: 0
    (0018,1184)    Y Focus Center                                      VR:
DS    Length: 2     Value: 0
    (0020,0032)    Image Position (Patient)                            VR:
DS    Length: 36     Value: -280.644600\-280.644600\1333.444600

I think, that origin of SPECT data should be readed as
-280.644600\-280.644600\1333.444600  (see the tag (0020,0032)) if I am not
mistaken, but ITK will read it as 0x0x0.

Thanks for any help!

Best regards to all ITK users, Michal.

Faculty of Biomedical Engineering, CTU

-- 
S pozdravem Bc. Michal Srna

Fotografické portfolio:
http://michalsrna.cz
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