Issue adding Private tags

[Carmelo]

Hi there,

I have been trying to add some private tags of my own using DCMTK to a DICOM file without success.

I have firstly created a project with the mkdicbi.cxx file

Then I modified the private.dic with the following:

(0029,"XXX",00) UL MyGroupLength 1
(0029,"XXX",01) DS MinTemperature 1
(0029,"XXX",02) DS MaxTemperature 1
(0029,"XXX",10) DS CameraTemperatureResolution 1

Then I generated the dcdictzz.cxx with the new private data and rebulid all the entire project.

Done all that, I put that and initially seems to work:

ds->putAndInsertString( DcmTagKey(0x0029, 0x0001), "25");
ds->putAndInsertString( DcmTagKey(0x0029, 0x0002), "35");
ds->putAndInsertString( DcmTagKey(0x0029, 0x0010), "1");
...

but then when I dump the file I get the following:

(0029,0001) UL 25 # 4, 1 PrivateGroupLengthToEnd
(0029,0010) LO [1] # 2, 1 PrivateCreator

Can anyone, please help me trying to know what happens here...thanks in advanced

cheers,
Carmelo

[Marco Eichelberg]

First of all, read the section in DICOM part 5 that explains how private elements work, including the reservation element.

An attribute that is encoded in private.dic as (0029,"XXX",00) means that in the dataset you find the following structure:

Code: Select all

(0029,0010) LO [XXX]
(0029,1000) UL 1234 # MyGroupLength

, or, more general,

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(0029,00YY) LO [XXX]
(0029,YY00) UL 1234 # MyGroupLength

.
As you see, "MyGroupLength" will never actually be a group length attribute, because the element number will always be >= 0x1000.

Secondly, when inserting new private elements into a dataset, you should explicitly pass the value representation because the dictionary lookup does not work at that point for private attributes where the VR depends on the reservation element value. Instead of using

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 ds->putAndInsertString( DcmTagKey(0x0029, 0x0001), "25"); 

, use

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 ds->putAndInsertString( DcmTag(0x0029, 0x1001, EVR_DS), "25"); 

[Carmelo]

Many thanks Marco.