How do I open the safe?

Hint 1 of 20:

In case you haven't found it, the safe is the item that you can take out of
the freezer in the room with the severed heads.

Hint 2 of 20:

Put the safe in the box on the left side of the machine next to the safe. 
Then, when you go for a close-up view of the safe, you'll be able to look at
its top.  That's where you'll find the dial.

Hint 3 of 20:

So now you need to look for the combination.

Hint 4 of 20:

Part of the machine is an x-ray device.