Released thyroid cancer patients treated with 131I may cause a radiation risk to their family members. However, no current regulations exist in Taiwan to limit the radiation dose among patients released post-treatment. This study assessed radiation exposure to caregivers of thyroid cancer patients treated with 131I to verify whether their doses exceed the 5-mSv limit per treatment session. The study population comprised 63 patients from four hospitals and their caregivers. Dose rates at a 1-m distance from patients were quantified before their release. Dosimetry data of caregivers were obtained using personalized thermoluminescent dosimetry badges. Upon the release of patients treated with 131I, Dose rates at a 1-m distance from the patients were 3.9–55 μSv/h. The radiation doses to caregivers ranged from 0.21 to 1.7 mSv after the patients released. When the 1-m dose rate of patients upon hospital release was 50 μSv/h, the highest possible radiation dose was assessed of 4.76 mSv for caregivers. In conclusion, as the dose rates at a 1-m distance from patients upon release were <50 μSv/h, the radiation dose received by their caregivers would be in accordance with the 5-mSv limit recommended by the International Atomic Energy Agency series 40, International Commission on Radiological Protection publication 94, and National Council on Radiation Protection and Measurements Report no. 155.