Do you have to pay tuition for summer term? At other schools, you don't usually pay, since you are just doing clinical rotations. I had assumed it was the same at Northwestern, but I could be wrong.
How did you get this figure? To my knowledge, you pay for 5 quarters of tuition at ~$18,000 per quarter. Their website also says work study opportunities are available, which reduces tuition by $3,000 per quarter. If you factor that in, the estimated cost of tuition is ~$75,000, which is similar to that of Stanford (and likely other private schools).