Yes, LOBOTOMY is a Scrabble word!

Letter values in Scrabble US: L 1, O 1, B 3, O 1, T 1, O 1, M 3, Y 4.

Is it a valid word?

LOBOTOMY is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

surgical interruption of nerve tracts to and from the frontal lobe of the brain; often results in marked cognitive and personality changes

Also: prefrontal lobotomy, prefrontal leukotomy, prefrontal leucotomy, frontal lobotomy.

Not playable in Scrabble US: LEUCOTOMY.