Currently an additonal helper node is used to visualize dose iso lines (this should also be changed, see T23355). In its current implementation this helper nodes are not properly managed/cleaned up (if its parent dose node is removed) when the dose visualization view is not open and active.

As long as we have no cleaner implementation for the mapping, at least visualizing doeses should not mess up the data storage.
To avoid this and make the current implemenetation a bit cleaner and more decoupled, the dose visualization plugin should have the single responsibility (generating, removing, etc) for the iso dose helper nodes. Code inother parts (e.g. DICOM editor) should be removed.