Yes, QUANTIZES is a Scrabble word!

Letter values in Scrabble US: Q 10, U 1, A 1, N 1, T 1, I 1, Z 10, E 1, S 1.

Is it a valid word?

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

approximate (a signal varying continuously in amplitude) by one whose amplitude is restricted to a prescribed set of discrete values
apply quantum theory to; restrict the number of possible values of (a quantity) or states of (a physical entity or system) so that certain variables can assume only certain discrete magnitudes that are integral multiples of a common factor

Not playable in Scrabble US: QUANTISE.