I Had Radiation For Prostate Cancer 4 Years Ago I,am

i had radiation for prostate cancer 4 years ago i,am 74 years old ,i,am in perfect shape otherwise and allways had a very active sex life but now even though i have no problem getting a erection it is really not hard and fully erect like it was before the radition also justa little clear liquid after intercourse! is there anything i can do to get afull erection ,or am i all done?