Putting password on your Microsoft Office Word Document

I am working in a psychological testing center in which there are times that I handle sensitive cases. These cases require high level confidentiality and if possible, only a minimum number of people be able to read the reports of these cases.
However, our computers are in a network and the administrator has set it to be accessible by others. Is there a way that I can put a password on the document or file alone and not on the whole folder?
