A Planning Comparison of 3D Conformal Multiple Static Field, Conformal Arc, and Volumetric Modulated Arc Therapy for the Delivery of Stereotactic Body Radiation Therapy for Lung Cancer

of SBRT, disappearance of symptoms, response of SBRT, and patient’s status and toxicities were evaluated. Results: There were 13 cases with metastatic thyroid carcinoma including 6 men and 7 women with a mean age of 46.85 years (range, 23-73 years) treated with SBRT. The papillary was the most common histologic type in 11 patients. The metastases of 5 patients were located in the cervical vertebra, 3 patients in lymph node, 3 patients in the skull and brain, 1 patient in the lung, as well as 1 patient in the ventricle, respectively. Themost common symptom atmetastases was pain,whichwaspresent in 5 patientswith cervical vertebrametastases. The tracking models contained vertebral spine tracking system (7 patients), skull tracking system (4 patients), fiducial tracking system (1 patient), and synchrony tracking system (1 patient), respectively. Themedian PTVof SBRTwas 8.05 cc (range, 2.50-72.66 cc). The patients received amedian five fractions (range, one to five fractions) with a median dose of 8 Gy per fraction (range, 6-23Gy). The median biologically equivalent dose (BED) was 59.5 Gy (range, 26.4-150 Gy). Thedosewasprescribed to themedian80%isodose line (range, 70-81%),which encompassed 95% of the PTV. To the end of the following-up, the metastatic sites of all patients were controlled, and the symptoms related to the metastases had relieved about one week after SBRT. There were 10 patients (76.9%) were alive without evidence of recurrence, and 3 patients (23.1%) died due to other reasons. In addition, no adverse events were observed. Conclusions: With excellent in-field local control and symptoms relieved without severe toxicities, SBRT for metastatic thyroid carcinoma seems to be feasible and safe for appropriately selected patients. Further research is warranted for more accurate selection of patients suitable for SBRT. Author Disclosure: H. Wang: None. M. Meng: None. C. Jiang: None. D. Qian: None. L. Zhao: None. Z. Yuan: None. P. Wang: None.