Ghouls: We all know them. They are a part of the daily life in every postapocalyptic settlement. Yes, even Diamond City. This gas mask isn't fooling anybody, Bobby.
For the most part, they are harmless, albeit unpleasant to the eye. They can be traders, doctors, mercenaries, farmers, chem addicts, just like everybody else.
But, if you leave the safety of your settlement and venture forth into the ruins, you will meet a whole different breed of ghouls: feral, bloodthirsty monsters,
which want nothing but one thing: to have you for dinner!

But, what is the cause of such a striking difference in behavior?
Why are some ghouls able to drink rum and cheat at poker, while others mindlessly shamble through the ruins and try to gnaw at the nearest scavenger?
And, how are they even still alive after being locked in in that building for over 200 years?

It is the opinion of this humble researcher, that these questions have the same answer: radiotrophy.
It is common knowledge that ghouls, both the lucid and the feral kind, are immune to radiation. However, what most don't know, is that they are also healed by it.
While regular human cells quickly die off, samples of ghoul tissue show an increased vitality when exposed to radioative material.
This is consistent with reports of increased wound healing while being in irradiated locations from ghouls.
It might also lend a grain of credibility to the tales of feral ghouls "reviving" when exposed to bursts of radiation, as told by certain types of scavengers.

The process which turns people into ghouls, probably somehow allows their cells to use radiation as an energy source for their metabolism.
However, since ionizing radiation causes significant damage to any tissue (any matter, strictly speaking), a mechanism to repair this damage is also required.
Therefore, the regenrative properties might very well be not a result of the ghoulification process, but a necessary prerequisite, whenever preexisting or aquired via mutation.

If true, then, given enough radiation, a ghoul would indeed be able to survive in an anaerobic environment, like a sealed pre-war cellar.
Of course, there is more needed than just metabolic energy.
And, it is questionable inhowfar radiotrophy could even provide enough of it to support a human body, without it suffering permanent damage.

And here we come back to the main question of this paper: Let's assume that a human could have survived the bombs, could have turned into a ghoul,
and was then sealed in an airtight, irradiated room without any food or water. Let's further assume that all bacteria was killed off by the radiation, effectively sterilizing the body, preventing decay.
Maybe the ghoul could use the radiation to keep mantaining the body, slowly repairing tissue damage as it occurs, using the materials the body still has to offer.
Would the energy the cells harvest be enough for anything else? For moving, thinking, or even having a heartbeat? Probably not.

And, most importantly: what happens to the subject's brain? Even if the new radiation-driven metabolism can repair the organ in general, the important part is it's structure.
Just having a bunch of neurons won't do you any good, it's their connections which matter! Your memories, thoughts, feelings, your You, so to speak, it's all within the connections of these cells!
If they are destroyed, whenever by a lack of oxygen, blunt-force trauma, or late-onset Alzheimer's: once gone, the best cell regeneration won't bring them back.
Most certainly, the regeneration does more harm than good here, restoring some basic, primal, and yes, feral state of the brain.

So, we end up with the feral ghoul as we know and hate it: dessicated, starving, only able to follow it's most basic urge: the urge to feed!
Now, why feral ghouls do not attack each other, and even seem to tolerate some of their lucid brethren, that is a topic for a different paper.