how to query LOB fields?

Hi,

How can I query a LOB field from Oracle using ROracle library?

library(ROracle)
drv <- dbDriver("Oracle")
connect.string <- paste(
  "(DESCRIPTION=",
  "(ADDRESS=(PROTOCOL=TCP)(HOST=", host, ")(PORT=", PORT, "))",
  "(CONNECT_DATA=(GLOBAL_NAME=",GLOBAL_NAME,")(SID=", SID, ")))", sep = "")
con <- ROracle::dbConnect(drv, username = username, password = password, dbname = connect.string)

I am a newbie and tried this:

rs <- dbSendQuery(con, "SELECT UTL_ENCODE.BASE64_ENCODE(CAST(LOB_FIELD AS RAW)) FROM TABLEDATA WHERE OTHER_FIELD = 'something'") 

data <- ROracle::fetch(rs)
# Error in .oci.SendQuery(conn, statement, data = data, prefetch = prefetch,  : 
  ORA-00906: missing left parenthesis


rs <- dbSendQuery(con, "SELECT dbms_lob.READ(LOB_FIELD) FROM TABLEDATA WHERE OTHER_FIELD = 'something'") 

data <- ROracle::fetch(rs)
#Error in .oci.SendQuery(conn, statement, data = data, prefetch = prefetch,  : 
  ORA-00904: "DBMS_LOB"."READ": invalid identifier