I'm 29 years old and going back to school to get my Doctorate. It is a 4 year program and I am not planning to work during those 4 years.

I have:
$30K in liquid savings
$40K Roth IRA
$50K in 403B
Zero Debt

Income of: $3,000 per month (for 4 months until school starts)
Expenses of: $1,000

My liquid savings is low due unexpected expenses the last few months.

Tuition for school is $31k per year
Living expenses per year is about $20,000
Student loans at 6.8% with interest accruing immediately

I am going to try to live the first year on my liquid savings, but am wondering if I should use my Roth IRA to pay for student loans end of year 1,2,3,4. This is because the interest rate of student loans is higher than what my Roth has been earning. Also, I can take my Roth money without penalty to pay for a university.

Do you have any other suggestions as to save for grad school or obtain low interest student loans?

Thank you very much!