You can deduct medical expenses for a person who is your dependent, or for a person who meets most of the qualifications to be a dependent but is disqualified because their taxable income is more than $4400 or they are married and filing a joint return with their spouse. However, this still means they must be a US citizen, a green card holder, or a resident alien (living in the US). So your father does not qualify.
See page 3
https://www.irs.gov/pub/irs-pdf/p502.pdf
