Stereotactic Radiotherapy for Adrenal Metastases: A Multi-Institutional Review of Patient Characteristics and Outcomes - Turkish Society for Radiation Oncology SBRT Group Study (Trod SBRT 10-004).

INTRODUCTION: This study aimed to report the outcomes of stereotactic body radiotherapy (SBRT) for adrenal metastasis in a retrospective multi-institutional cohort. METHODS: The outcomes of 124 patients with 146 adrenal metastases who underwent SBRT within 11 years (2008-2019) were retrospectively evaluated. Survival outcomes were analyzed by the Kaplan-Meier method. Patient, tumor, and treatment characteristics and their effects on survival, local control (LC), and toxicity outcomes were analyzed by log-rank and multivariate Cox regression methods. RESULTS: The median age was 60 years. The most frequent primary tumor site was the lung, followed by the gastrointestinal system and breast. The adrenal gland was the only metastatic site in 49 (40%) patients. Median biologically effective dose (BED)10 was 61 Gy. The overall LC rate was 83%, and it was positively correlated with the BED10 and fraction dose. The 1- and 2-year local recurrence-free survival, overall survival (OS), and progression-free survival (PFS) rate was 79% and 69%, 83% and 60%, and 31% and 12%, respectively. OS significantly improved with non-lung cancer and <4-cm lesion and PFS with a fraction dose ≥8 Gy, BED10 >65 Gy, and an isolated adrenal metastasis. Fourteen patients reported an acute toxicity, and late toxicity was observed in 3 patients, including one grade 5. CONCLUSION: A satisfactory LC rate was achieved for adrenal metastasis via SBRT. A higher BED10 and fraction dose were positive prognostic factors for tumor control. However, the main problem is DM in these patients, and systemic treatment options are needed to be improved.

Reduction of S-parameter errors using singular spectrum analysis.

A free space measurement method, which consists of two horn antennas, a network analyzer, two frequency extenders, and a sample holder, is used to measure transmission (S21) coefficients in 75-110 GHz (W-Band) frequency range. Singular spectrum analysis method is presented to eliminate the error and noise of raw S21 data after calibration and measurement processes. The proposed model can be applied easily to remove the repeated calibration process for each sample measurement. Hence, smooth, reliable, and accurate data are obtained to determine the dielectric properties of materials. In addition, the dielectric constant of materials (paper, polyvinylchloride-PVC, Ultralam® 3850HT, and glass) is calculated by thin sheet approximation and Newton-Raphson extracting techniques using a filtered S21 transmission parameter.