Every state and hospital has different regulations. Your chances are better for a job as an orderly or other non-licensed job than a doctor or a nurse.
In Canada there is a new legislation that requires a criminal background check for the health care industry.
In the United States a background check is standard for most health care jobs. The higher the position the less tolerant employers are about criminal records.
If you were just charged than employers may have more leniency than if you were convicted.
Assault and battery? The odds are against you. To work in the medical field you need to be able to deal with difficult situations with a cool head ... the fact that you've gone to the extent of actually hurting someone proves you don't have that ability.
I'm afraid the only way you'll ever get hired into the medical field is if you know someone who can pull strings.
You should be able to as long as you aren't charged with a felony, but with a charge at all decreases your chances of getting the job