Is it possible to get only one Field from a Document?

I have a environment where we have indexed a DB with about 6mil entries
with Lucene, and each row has 25 columns. 20 cols have integer codes
used as filters (indexed/unstored), and the other 5 have (very) large
texts (also indexed/unstored). Currently the search I'm doing is like this:

Hits hits = searcher.search(query);
for (int i = 0; i < this.hits.length(); i++) {
Document doc = this.hits.doc(i);
String s = doc.get("fieldWanted");
// does everything with the result, etc
}

We are trying to reduce memory usage, however. Is it possible to return
a Document object with just the Fields I really need? In the example,
each Document have 25 fields, and I just need one... would this
theoretically make any difference?