There are two issues here. One is about effect of radioiodine treatment on chances of pregnancy and other is its effect on outcome of pregnancy. Transient ovarian failure has been reported after treatment with high dose of radioiodine but for an individual, chances of conception are very high. Genetic damage has also been not reported in the offsprings of these patients. So don't worry about these two issues and go ahead for pregnancy once your treating nuclear medicine specialist clears you for this i.e., he feels there are no chances recurrence in near future.