Trying to extract dose information from the headers of CT images is
fraught with issues, not the least of which is different
interpretations by different vendors of the meaning of some of the
attributes for helical scans. That is why DICOM has devoted effort to
define a CT Radiation Dose Report (Supplement 127, now in Ballot).
Because there is increasing demand from regulatory agencies around the
world for more accurate dose information, there should be relatively
rapid implementation of this new object by the manufacturers - and if
there isn't, you as customers must complain loudly! Please contact
your equipment manufacturer and ask specifically when they will
provide the CT Radiation Dose Report capability as a software upgrade
for your machine.

(not speaking as an employee of GE Healthcare!)