Should "LastUpdate" of a study also be updated if an instance of a study is deleted

Hi all,

Recently I’ve been a bit puzzled by the “LastUpdate” field in a study. It correctly tracks the last time an instance for a particular study has been added to the Orthanc database.

However, should an instance be deleted, this field isn’t modified.

Looking at the documentation in more detail, I think that this is technically correct:

LastUpdate records, for each patient/study/series, the last time a DICOM instance was added to this resource.

Is that correct? Also updating it whenever an instance is deleted would be useful to me, but maybe it isn’t inline with what people generally expect from DICOM??


The documentation is correct: “LastUpdate” changes when new content is added (not removed).

You can track the removal of instances by using a plugin and the “OrthancPluginRegisterOnChangeCallback()” primitive:


Thanks, that clears that up for me.

The plugin seems like a useful thing, but I think I’ll just make my application resilient against missing instances, and that way we’ll have that covered too.


Fine, glad to read you have a solution!