It seems like Indiana Jones has sent us on a wild plutonium chase. The Ghostbusters don't use plutonium guns...they use proton packs. They did, however, say that they detected some radioactivity at The Art Institute of Chicago on a remote ghost-removal call they made a few weeks ago.
Follow the lead and search for any information that might be helpful. Everything you need should be in this room.
Once you find the information you need, meet back up in Glenbrook High School for detention.
If you need a hint, remember to check the room description!
I could stare at these paintings forever.