I am an associate doctor under contract until 2013. Is it my right to give a reasonable notice of 30-45 days and end my contract early?

What does your contract say?  It may well have provisions about the required notice, refraining from competition even after the termination of your employ, and other applicable provisions.  Assuming that your contract does not allow you to terminate early (and assuming you have no grounds for claiming a material breach of the contract by your employer) and assuming that Maryland law (I presume, since I don't know any other facts other than the state from which you sent this inquiry, that Maryland law will govern your contract) is substantially the same as the law in the jurisdictions in which I usually practice, you will have breached your contract if you quit before the end of its term.  While your employer cannot force you to continue working for him/her/it, it may be able to have you enjoined from working as a doctor until the end of your contract.  Although such an injunction would be unlikely in the case of a run of the mill employee who does not possess special skills, it is much more likely when the employee is a medical doctor.