A data.frame of tags to look up in DICOM
header. Not an exhaustive list, but extensive.
dicom_tagsA data.frame with 6 columns
the tag identifier for the field
the name of the field
no space version of name - a better lookup ID
value representation
value multiplier
indication of retired tag
Adapted from http://dicom.nema.org/dicom/2013/output/chtml/part06/chapter_6.html