The goal of this study is to learn if a decision aid (DA) website helps people with thyroid cancer make informed decisions about radioactive iodine (RAI) treatment. The main questions it aims to answer are: - Does the decision aid help participants understand the risks and benefits of RAI treatment? - Does it help participants make choices that reflect what matters most to them? - How does the decision aid compare to usual care in supporting patients through this decision? Participants who have been recently diagnosed with intermediate-risk differentiated thyroid cancer (DTC) will be randomly assigned to one of two groups. One group will receive a special decision aid website. This site includes detailed information about RAI, short videos, drop-down menus with extra details, exercises to help clarify values, and tools to help patients prepare questions for their doctor. The other group will receive the American Cancer Society (ACS) website. This site gives basic information about RAI but does not include interactive tools and is not specific to intermediate-risk thyroid cancer. Follow up surveys will be sent to the participants periodically, first at the start of the study, and again at 1 week, 4 weeks, and 6 months later. Researchers will compare how the two groups differ in making informed decisions. The decision aid is meant to support, not replace, a conversation with the medical team. Doctor recommendations remain an important part of treatment decisions.