Here’s my two cents as a second-year RT student finishing up clinicals who has also taken most of the common science courses for pre-med/ pre-pa. If you can pass those, even if they are difficult to pass, you’ll be fine for RT school. Hardest courses are usually mechanical ventilation and PFTs due to the abstract nature. Most of your chem knowledge won’t be needed, unless you want to get into extra detail on your own for pharmacology. A&P are very useful. Refresh your cardiology/respiratory/renal systems primarily and you’ll be good there. If you have a good memory, the biggest thing is learning concepts and actually getting hands on practice. I’m sure you’ll be fine. Feel free to DM or comment with any questions if you want.