Feasibility and Tolerability of Surface Guided Radiotherapy in Breath-Hold Liver Stereotactic Body Radiotherapy

Background: Intra-fractional motion is one of the main challenges in SBRT. Breath-hold (BH) technique minimizes the tumor motion. However, reproducibility and consistency are critically important. Surface tracking systems integrated into treatment enable motion tracking with three-dimensional camera technology. Surface guidance was integrated with Varian EDGE and used at multiple treatment sites since 2018 in our department. After four years of experience, in this study, we aim to publish patient-reported outcomes (PROMs), feasibility, and tolerability of surface guidance (SGRT) with breath-hold SBRT in a specific subgroup: liver metastases. Methods: Patients with liver metastasis treated with breath-hold and SGRT were evaluated prospectively. Two-step, seven-question surveys were applied after CT simulation and treatment. Treatment duration and BH number were recorded. In addition, factors that can affect the SGRT and treatment time were evaluated. Results: Between April 2021- May 2022, 41 patients were treated in 171 fractions. According to the PROMs, previous training was beneficial, and holding breath is tolerable. Patients have a little stress about taking an active role in the treatment. Karnosky performance status (KPS), age, lung volume, or any condition affecting lung capacity, previous BH history, and being a native speaker are not correlated with treatment time and BH with SGRT tolerability. Only female patients have better BH performance with SGRT treatments than male patients (p: 0,02). Conclusion: SGRT applications in BH are tolerable and feasible in liver SBRT treatments. There is no specific subgroup that cannot be tolerated with this method.