A doubt about cancer. Treating ny fear!

Hi dr,my sister had radioiodine therapy after post op thyroidectomy for papillary CA 2 months back. I was advised by the nurse that i should not enter her room FOR 2hours after she take the iodine pill. After that i can go and give her food and should come out and stay in attender room. For 2hours i didnt enter but after 2hours, i felt sad for her to keep her alone so i sat in her room in a chair of 5metre distance and i didnt touch her. I forgot radiation risk and was there for 3 hours and nurse asked me to come out..... I just scared that i may get leukemia or thyroid cancer. I feel always fatigue... I am scared of it dr... Can you tell me what percentage i can get cancer in the future.. Should i take a blood test or smear for treating ny fear