Optional module activation criteria

[pbrunnen]

Dear all,
I had a standards question with regard to optional modules within an IOD and when they become active.

When is an optional module considered 'active / in use'? I believed it was whenever any element of that module is used that is exclusive to the module, but I would like confirmation from experts. My attempts to decipher this from the text in part 3, chapter A and chapter C are not clear.

So for example using SOP Class 1.2.840.10008.5.1.4.1.1.7.3 (Multiframe Grayscale Word Secondary Capture Image Storage):
- NumberOfFrames (0028,0008) is a type 1 in the mandatory 'Multi-Frame' module and a type 1 in the optional 'Multi-frame Functional Groups' module; setting NumberOfFrames does not invoke the optional module.
- InstanceNumber (0020,0013) is type 2 in the mandatory 'General Image' module but type 1 in the optional 'Multi-frame Functional Groups' module; setting InstanceNumber to a non-Null value would invoke the optional module.

Thank you.

[Marco Eichelberg]

It is correct that an optional module is considered present when any attribute is present that is exclusive to that module.

So yes, NumberOfFrames (0028,0008) is type 1 in both the Multi-Frame module (which is mandatory for this SOP class) or the Multi-frame Functional Groups module (which is optional for this SOP class). The presence of NumberOfFrames (0028,0008) in the dataset, therefore, does not automatically "invoke" the Multi-frame Functional Groups module.

I do not agree that setting InstanceNumber (0020,0013) to a non-Null value would invoke the optional 'Multi-frame Functional Groups' module. A type 2 attribute should be populated with a value and may only remain empty if the value is not known. Therefore, the presence of InstanceNumber may as well mean that the General Image Module has been invoked.

The presence of the Shared Functional Groups Sequence (5200,9229) would definitely mean that the 'Multi-frame Functional Groups' module has been invoked, though, since it is type 1 in that module and exclusive for that module.

[pbrunnen]

Ok, so my verification tests may be in error. Many Thanks for the assistance!