wanting to become radiation therapist

hey guys, i’m 20 & i’m finishing my last year at university for a psych degree. but i’m looking to switch paths into becoming a radiation therapist, so i have a couple questions. what grades did you get in high school to be accepted into your program? this summer i’m retaking some high school classes because i didn’t do well in grade 12. will they look at my university marks considering they’re unrelated? what is the workload like? is it very math heavy? any & all other information would be super helpful🫶