If you’re just starting out, may I refer you to the LOINC RSNA Playbook in the User’s Guide? It starts on page 185. If you downloaded the LOINC/RELMA zip file you’ll find it on your local machine at LOINCUsersGuide.pdf
The formatting of the radiology terms may make more sense to you after reviewing.
To add to what Pam said, LOINC codes are made based on user requests. Many inconsistencies stem from the original requests, for example, where a user may have only requested a code for the right side and not the left. In recent years, when we spot these inconsistencies we follow up with the user and recommend creating a complete set of codes, but that did not happen as consistently in the earlier years of LOINC.