There is currently no reason to use Aceton Beam. It's in the running, IMO, for least useful ability.
It is only available on ships with lousy turn rates, and has a 90 degree firing arc. The ships you would most likely want to use it on will have the easiest time staying out of your front arc.
It shares Boff slots with heals that are more reliable. Aux2Sif and Extend Shields are more dependable for keeping people alive. It might be helpful to drop an enemy's offense by 50%, but if they're not in your front arc it won't happen, while ES will help you out-heal their damage and you get a 360 firing field.
So, defensively Aceton Beam is pretty lacking. Offensively the radiation damage is nothing I've ever noticed.
Give us an Aceton Beam Doff.
1. Reduce incoming healing by X%. Currently STO is set up so that a large spike of damage is done with somebody attempting to out-heal it. This would be interesting because escorts wouldn't be able to run this ability and would need some teamwork with cruisers to really capitalize on it.
2. Aceton Beam, once applied, has X% chance to spread to friendly ships.
3. Turn rate/movement debuff. Shmeh. I probably still wouldn't take it.
4. Chance to re-apply after cleared. Still shmeh.
5. Increase in radiation damage. Just a lazy buff. Again, probably wouldn't take it.
The Doff needs to be useful enough justify a Boff and a Doff slot. Sorry if I'm stating the obvious, but it has to beat out other things, right?
An increase in Aceton Beam's usefulness (a buff for the debuff, lol) would also be a buff for Engineering Team. Currently Tactical Team is king, IMO, and this is a way to shift some balance without coming at the Teams directly.