ESTRO 2023 - Abstract Book

S1774

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ESTRO 2023

Materials and Methods Strict selection criteria included tumor and patients’ characteristics ( Table 1 ). Patients not eligible for surgery with early- stage NSCLC or oligometastatic lung tumors, PS ECOG 0-1, with a single nodule, in peripheral location were included. During the simulation phase, a 4D-CT scan was performed (10 respiratory phases). GTV was contoured on maximum expiration phase scan. PTV was obtained by adding an isotropic expansion margin of 3 mm to the GTV. Tracking target volume was also contoured. A LINAC-based plan was carried out for back-up. In this case an Internal Target Volume (ITV) on the Average scan was acquired from the GTV contoured on the 0% phase scan. Before treatment, patients had to undergo a simulation session (during which the treatment beam is disabled) to verify the feasibility of the respiratory model and patient’s compliance and to test the 2D radiographs consistency ( Figure 1 ). In the event of an unsuccessful simulation phase, patients would be treated according to a LINAC-ITV-based plan. Respiratory toxicity was evaluated with the CTCAE 5.0 grading. Table 1 . Inclusion criteria based on tumor and patients related factors for Radixact® Synchrony® Lung SABR treatments.

Figure 1 . Target visualization on Synchrony® respiratory tracking system.

Results From July 2020 to July 2022, 18 patients were enrolled. Of these, 12 were affected by ES-NSCLC and 6 had lung metastases. The median age was 75 years old. All patients completed the simulation phase successfully and were treated with the Synchrony® plan conforming to a “risk adapted” fractionation schedule (3-5 fractions). The median beam-on time for each