Note: Capitalize your operators as a matter of practice. In some platforms or search systems, it does not matter whether you enter them in uppercase or lowercase, but others (like Google Scholar) require them to be in uppercase to work properly.
Use parentheses to set the order of execution of the Boolean logic. Parentheses work in most but not all systems (e.g., they work on the Ovid, PubMed, EBSCOhost, ProQuest, Scopus, and Web of Science platforms, but they are ignored in Google and Google Scholar)
e.g., (chest OR thorax OR thoracic) AND (imaging OR radiographs OR radiography)
Boolean operators can be placed between your search terms to narrow or broaden a search, or to exclude search terms.
You will find below a brief video on how to use the Boolean operators: