S1070
Clinical – Upper GI
ESTRO 2026
Characteristics for eight patients are summarised in Table 1. The majority (n = 5) were prescribed 50 Gy, the remainder 40, 45 or 60 Gy. Median Acc GTV D95% was slightly higher than RefPlan: 51.9 Gy (range: 38.1 – 70.0 Gy) vs 50.3 Gy (range: 38.8 – 67.4 Gy). Median Acc uninvolved liver Dmean was similar to RefPlan (Table 1). Other OAR Acc doses were similar or lower than RefPlan (Fig 1).At clinical review 4-6 weeks post-SABR, reported side-effects included thirteen grade (G)1, most commonly nausea and diarrhoea, and two G2 fatigue. Approximately 3 months post-SABR, three G1 side-effects (fatigue, diarrhoea, bloating) and one G2 (fatigue) were reported. No acute side-effects > G2 were reported. No radiation induced liver damage (RILD) was observed.Radiological local progression was observed in two patients, at 3.8 months (hepatocellular carcinoma - HCC) and 11.5 months (intrahepatic cholangiocarcinoma - iCCA) post-SABR. One patient died from metastatic disease after 16.9 months.
selected HCC patients. Keywords: Hepatocellular-carcinoma, SBRT, Local- Control
Digital Poster 874
Deformable registration-based accumulated dose and patient outcomes for MR-guided liver SABR Mairead Daly 1 , Agnieszka Zakacz 1 , Rekaya Shabbir 1 , Ruksana Sivakaran 2 , Eliana Vasquez Osorio 1 , Marianna Theodoulou 2 , Zainul Kapacee 2 , Amarjot Chander 3 , Prakash Manoharan 3 , Ganesh Radhakrishna 2 , Laura J Forker 2 , Ananya Choudhury 1,2 , Cynthia L Eccles 4 1 Division of Cancer Sciences, University of Manchester, Manchester, United Kingdom. 2 Department of Clinical Oncology, The Christie NHS Foundation Trust, Manchester, United Kingdom. 3 Department of Radiology, The Christie NHS Foundation Trust, Manchester, United Kingdom. 4 Radiotherapy Department, The Christie NHS Foundation Trust, Manchester, United Kingdom Purpose/Objective: Magnetic resonance (MR)-guided adaptive stereotactic ablative radiotherapy (SABR) enables daily adaptation using superior soft-tissue contrast over cone beam computed tomography (CBCT), particularly for tumours poorly visualised on CBCT or adjacent to organs at risk (OARs) (1). However, due to daily anatomical variation, the total cumulative dose is not known. This work quantified accumulated dose using organ-wise (OW) deformable image registration (DIR) for MR-guided adaptive liver SABR on the MR Linac and evaluated patient outcomes and acute side effects. Material/Methods: Patients treated with adaptive liver SABR in 5 fractions (#) on the MR Linac on an ethics-approved registry study (NCT0407530, (2)) were included. The clinical reference plan (RefPlan), motion-compensated 3D VANE planning MRI (pMRI), daily pre-treatment MRI (FxMRI), and associated structure sets created in Monaco (V5.51.11) were retrospectively collected. OARs were recontoured throughout the treated volume.In RayStation (V12), OW DIRs initialised using OW rigid frame-of-reference registrations were created between pMRI and each FxMRI (3). Re- contoured OARs served as control structures in one registration per organ, per scan. Fraction doses were deformably mapped and summed. Gross tumour volume (GTV) and OAR dose differences between RefPlan and accumulated (Acc) were analysed using descriptive statistics. Patient outcomes, local failure, and side-effects were retrospectively collected from the patient record. Results:
Made with FlippingBook - Share PDF online