Withdrawing from IRA for medical expenses?

Hello, can I withdraw money from my IRA for Medical expenses that exceed 7.5% of my AGI?? Since Im married this would be our joint AGI correct?? Also if the expenses exceed 7.5% but are not more than the standard deduction and I cannot itemize, will I get penalized the 10% still? Also does the services rendered have to be the same year as the payment or are prepayments in 09 good for procedures in Jan 2010??