Just stepping away is in all likelihood exactly as much precaution as is needed: the machine itself ought to have shielding in all directions except the for the

Just stepping away is in all likelihood exactly as much precaution as is needed: the machine itself ought to have shielding in all directions except the for the beam itself, so it doesn't emit significantly in the other directions anyway and getting some distance kills even that on its own. Honestly, going outside as a way to ensure you don't stand in the beam by mistake might be the most important part.