When working with claims data from US - the LT and RT modifiers are in OMOP vocab twice.
under CPT4
https://athena.ohdsi.org/search-terms/terms/45888271
under HCPCS
https://athena.ohdsi.org/search-terms/terms/2720905
Make the first non-standard and map it to the second.
Addition: OMG! All modifiers are in Athena twice!!!