Thyroid cancer is the most common cancer of the endocrine system, and its preva‎lence is increasing. Recently, in nuclear medicine, radiopharmaceuticals called ”Theranostics” such as lutetium-177 FAP, a new radiopharmaceutical ”PET” with imaging capabilities during treatment have recently been used for thyroid cancer. This disease is completely cured by surgery or iodine therapy in most patients. But the disease is progressive in 5 percent of patients who are often resistant to iodine. It should be mentioned that effective chemotherapy is not available in thyroid cancer. In the present study, we intend to use 68Ga PET/CT images taken in patients with thyroid cancer resistant to iodine therapy, dosimetry using GATE code Monte Carlo simulation to check the adequacy of radiation therapy to patients’ tumors using 177Lu Do FAPI. It should be mentioned that there has been no reported case of treatment with radiopharmaceutical FAPI in patients with progressive thyroid cancer resistant to iodine therapy. Our recent imaging has confirmed the accumulation of radiopharmaceutical FAPI in the tumors of patients with progressive thyroid cancer resistant to iodine therapy. Results: In this research, due to the short range of beta particles emitted from luteum and the importance of its use in the treatment of metastatic tumors, this radiopharmaceutical was used to perform patient-specific dosimetry and its clinical examination. As expected, lutetium-177 FAP accumulated well in metastatic tumors. Also, due to having gamma radiation, it can also reduce pain. According to the calculations, the kidney is the organ that received the highest dose, and after that Bladder and metastatic tumors have also absorbed a higher dose. Therefore, these organs are considered sensitive organs.

مريم حسنوند , ايرج عابدي

مهرشاد عباسي , مازيار ايران نژاد

احمد شيراني بيد آبادي , حميده شاكري پور