So i have two stray kittens with ringworm?

I've been treating them both for over a week almost two weeks now. One never got more than one spot. The other had many patched of no hair. He looks sooo much better now. And i see no new spots forming. Is there a way I can be sure they are ok to be let back out of quarantine? Like I don't want to let them out of the back room into the house if they still have ringworm spores on their bodies. Is there a way i can check without going back to the vet again. I've spent over 300 bux so far and that's because he missed the ringworm the first trip and I noticed it later that week. So I had to pay for another visit plus very expensive meds. He says they shouldn't be contagious after a week of treatment, but I want to be sure. Thanks.