Hey there. I just came back from meeting with an endocrinologist who was really good at addressing these concerns (she brought up the subject before I got a chance to ask!)
According to her, there are no shown long-term effects of radiation treatment (low/moderate I'm assuming) on the ovaries or eggs. They do ask women to wait 6 months before conceiving after radiation treatment, but that's actually not due to any residual radiation, it's because you will probably be hypothyroid (low thyroid hormone) during this time, as they adjust your levels to find the right dosage. It has been shown that low thyroid hormone during pregnancy can adversely affect the IQ level of your baby, so they want to avoid that.
I was definitely concerned about the effect of radiation on the ovaries, but she says it isn't an issue, and I have no reason to not believe her, as she seemed smart, confident, and concerned for my health in all regards.
Hope that helps - also, don't be afraid to ask your own doctor for their opinions, maybe using this info as a starting point.