Modality, which is defined by the standard as "Type of equipment that originally acquired the data used to create the images in this Series", and is expected to take one of the values from this list. However,
Modalityis not equivalent to
SOPClassUID, and should not be used as a substitute. As an example it is possible that data derived from the original modality could be saved as a different object class, but keep the value of modality identical.