(1) tab_act

    This table probably records "Table actual" motion.  It occasionally 
    shows very high values for LONG & HEIG fields, which could correspond 
    to manual table motions following scans.

(2) vol_reg

    This table seems to have REG_XXX which are the registration results
    and SHIFT_XXX which are the motions after converting to corrections.
    There are no fields in the table for couch rotation or 
    hexapod rotations here.

    Registrations seem to be in mm relative to isocenter, as evidenced 
    by morning QA data.

(3) iso_cntr

    This table has the isocenter in both dicom and iso coordinates.

(4) ctvolume

    The coordinates in this table are most likely the default viewing 
    center.  
