If you are on Release 4.6.6, upgrade to Release 5.2/5.2.1 following instructions in the Oracle Clinical Upgrade Guide Release 5.2/5.2.1.
Note:
You do NOT need to install the 5.2/5.2.1 application tier because the technology stack is new in Release 5.2.2 and you must do a fresh install of the whole application tier.