Pixel data sequence

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angad
Posts: 112
Joined: Thu, 2010-02-18, 09:54

Pixel data sequence

#1 Post by angad » Fri, 2012-08-17, 06:28

Hi All,

I have one image(DX modality) where there is side mark "R" on the image...When i am opening this image in my viewer, side mark "R" is not coming, but the same thing is coming in ezDicom and eFIlm....

Pixel data is coming in sequence tag... following is the dcmdump :


(0054,0220) SQ (Sequence with explicit length #=1) # 72, 1 ViewCodeSequence
(fffe,e000) na (Item with explicit length #=4) # 64, 1 Item
(0008,0000) UL 52 # 4, 1 IdentifyingGroupLength
(0008,0100) SH [R-10214] # 8, 1 CodeValue
(0008,0102) SH [SNM3] # 4, 1 CodingSchemeDesignator
(0008,0104) LO [postero-anterior] # 16, 1 CodeMeaning
(fffe,e00d) na (ItemDelimitationItem for re-encoding) # 0, 0 ItemDelimitationItem
(fffe,e0dd) na (SequenceDelimitationItem for re-encod.) # 0, 0 SequenceDelimitationItem
(2050,0000) UL 16 # 4, 1 PresentationLUTGroupLength
(2050,0020) CS [IDENTITY] # 8, 1 PresentationLUTShape
(7fe0,0000) UL 6830106 # 4, 1 PixelDataGroupLength
(7fe0,0010) OB (PixelSequence #=2) # u/l, 1 PixelData
(fffe,e000) pi 00\00\00\00 # 4, 1 Item
(fffe,e000) pi ff\d8\ff\e0\00\10\4a\46\49\46\00\01\01\00\00\01\00\01\00\00\ff\c3... # 6830066, 1 Item
(fffe,e0dd) na (SequenceDelimitationItem) # 0, 0 SequenceDelimitationItem

In following way, i am reading the dicom file :

if(dataset->findAndGetUint16Array(DCM_PixelData,(const Uint16 *&)pUINT16).bad() || pUINT16 == NULL)
{

}

Can anyone suggest me how to get this side mark on image...

Thanks in advance !!!!

Thanks,
Angad Nath

angad
Posts: 112
Joined: Thu, 2010-02-18, 09:54

Re: Pixel data sequence

#2 Post by angad » Fri, 2012-08-17, 07:07

Pixel data is coming as data type "OB" and we are using findAndGetUint16Array API to get the PIXEL DATA.... Is it correct ?

Thanks,
Angad Nath

angad
Posts: 112
Joined: Thu, 2010-02-18, 09:54

Re: Pixel data sequence

#3 Post by angad » Fri, 2012-08-17, 07:39

I think i have to use DcmPixelSequence() class to get the DcmElement...

Am i right ?

Thanks,
Angad Nath

J. Riesmeier
DCMTK Developer
Posts: 2038
Joined: Tue, 2011-05-03, 14:38
Location: Oldenburg, Germany
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Re: Pixel data sequence

#4 Post by J. Riesmeier » Mon, 2012-08-20, 07:33

If you want to access the compressed pixel data, read the following HOWTO. If you want to access the decompressed pixel data, you should register the appropriate decoder(s) and call chooseRepresentation(EXS_LittleEndianExplicit, ...) on the compressed dataset. Of course, using the DicomImage class would also help (with the decoders registered before loading an image).

angad
Posts: 112
Joined: Thu, 2010-02-18, 09:54

Re: Pixel data sequence

#5 Post by angad » Tue, 2012-08-21, 05:48

Hi,

Thanks for your reply.

My problem is not how to read the compressed pixel data. For DX images, some side mark(label) like "R" is coming on the image. But when i am displaying this image in viewer, side marker(labels) are not coming. A black space is coming there.EZDicom is opening that image correctly with side markers on it....

I created the bmp file also using DicomImage Class. But in bmp file also, side markers are not coming....

Can you tell me in which tags these side markers are coming(either these values are coming in pixel data tag or there is some another tag like Laterality, Image Laterality etc). I changed the Laterality from "R" to "L", but after doing that also its showing "R" only in ezDicom.....Also if i change window level , window width in ezDicom for this image, these side markers are remaining constants.

I am sending the file to your email id(dicom@offis.de) for your reference.

Thanks in advance...

Angad Nath

J. Riesmeier
DCMTK Developer
Posts: 2038
Joined: Tue, 2011-05-03, 14:38
Location: Oldenburg, Germany
Contact:

Re: Pixel data sequence

#6 Post by J. Riesmeier » Tue, 2012-08-21, 07:54

I checked the DICOM image: As far as I can see, there is no side marker on the image. There is only a strange box near the right shoulder.

angad
Posts: 112
Joined: Thu, 2010-02-18, 09:54

Re: Pixel data sequence

#7 Post by angad » Tue, 2012-08-21, 08:42

yes, right...But when you open the same image in any another viewer(like ezDicom), "R" will come in this strange box....I don't understand how ezDicom is showing "R" on the image.....

J. Riesmeier
DCMTK Developer
Posts: 2038
Joined: Tue, 2011-05-03, 14:38
Location: Oldenburg, Germany
Contact:

Re: Pixel data sequence

#8 Post by J. Riesmeier » Tue, 2012-08-21, 08:44

Did you already check other DICOM viewer than ezDICOM? If not, please do so ...

angad
Posts: 112
Joined: Thu, 2010-02-18, 09:54

Re: Pixel data sequence

#9 Post by angad » Tue, 2012-08-21, 10:19

yes its coming fine in osirix and efilm also....

J. Riesmeier
DCMTK Developer
Posts: 2038
Joined: Tue, 2011-05-03, 14:38
Location: Oldenburg, Germany
Contact:

Re: Pixel data sequence

#10 Post by J. Riesmeier » Tue, 2012-08-21, 11:23

Is the marker/label at the same position as the "box" when rendering the image with DCMTK?

angad
Posts: 112
Joined: Thu, 2010-02-18, 09:54

Re: Pixel data sequence

#11 Post by angad » Tue, 2012-08-21, 11:33

Yes, exactly the same position....One black box is coming with "R" written on it....

J. Riesmeier
DCMTK Developer
Posts: 2038
Joined: Tue, 2011-05-03, 14:38
Location: Oldenburg, Germany
Contact:

Re: Pixel data sequence

#12 Post by J. Riesmeier » Tue, 2012-08-21, 11:41

Then it could also be a JPEG decompression issue ... very strange. In order to validate this, could you please decompress the DICOM image with dcmdjpeg and feed the resulting (uncompressed) DICOM image into ezDICOM, OsiriX and/or eFilm.

angad
Posts: 112
Joined: Thu, 2010-02-18, 09:54

Re: Pixel data sequence

#13 Post by angad » Tue, 2012-08-21, 12:19

after decompressing also, its opening exactly fine in ezDicom and efilm....

One more thing which i want to add is : efilm is not showing the side markers clearly(for both compressed and decompressed fomat). But if you use magnifier over the image, it shows "R" clearly...or if you change the window width / window level beyond the limit like (5500 / 0), efilm shows it clearly...

But side marker quality is same for both compressed and decompressed image....

Thanks,
Angad Nath

angad
Posts: 112
Joined: Thu, 2010-02-18, 09:54

Re: Pixel data sequence

#14 Post by angad » Wed, 2012-08-22, 07:20

Hi,

Any luck with my last post.

Is there any bug in dcmtk due to which side markers are not coming ?

Thanks,
Angad Nath

J. Riesmeier
DCMTK Developer
Posts: 2038
Joined: Tue, 2011-05-03, 14:38
Location: Oldenburg, Germany
Contact:

Re: Pixel data sequence

#15 Post by J. Riesmeier » Wed, 2012-08-22, 10:24

I've no idea. We need to check this more thoroughly. Therefore, I've added this issue to our internal to-do/bug list.

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