ESTRO 2025 - Abstract Book

S1555

Clinical – Mixed sites & palliation

ESTRO 2025

3330

Digital Poster Feasibility and accuracy of simulation-free (SF-RT) versus CT simulation based (CT-RT) Radiation Therapy in routine practice for palliative radiation Mansi Barthwal, Saumya Negi, Vipul Nautiyal, Viney Kumar, Anmol Mahani, Ravi Kant, Rishabh Dobhal, Jyoti Rawat Radiation Oncology, Himalayan Institute of Medical Sciences, Dehradun, India Purpose/Objective: Due to huge burden of oncology patients in low-middle income countries (LMIC) and advanced disease at presentation, a large majority of patients tend to get waitlisted for palliative radiation CT simulation scans. We looked into feasibility of SF-RT for palliative radiation to prevent delays in symptom relief. Material/Methods: In a single-institution, retrospective cohort study, all patients receiving palliative radiation at an Indian tertiary oncology center between April 2021 and September 2024 were eligible for inclusion into the study. Patients received both single and multi-fraction regimens. All patients underwent immobilization procedure followed by radiation planning. Coprimary endpoints were SFRT utilization, impact on time between decision making and treatment delivery, and difference in treatment shifts on the day of first radiation. Results: In a span of three-and-a-half year, a total of 322 courses of palliative radiation were delivered. Thirty four percent of these were SF-RT. Mean age was 57 years (range 10 to 87 years). All patients were treated on an outpatient basis. Most common primary diagnosis was that of thoracic malignancy (n=89) and breast (n=38), comprising 39.4% of all sessions. Pelvis (n=112) was the most frequently treated site followed by spine (n=84), and brain (n=64). Forty percent courses in SF-RT group were delivered as simultaneous multi-site radiation as compared to 24% in CT-RT group. Mean time between scan import to planning system and plan approval was 0.28 days for SF-RT and 0.43 days for CT-RT. Similarly, mean time between scan import and first treatment was shorter in SF-RT group (1.5 days vs 1.9 days). The mean shift in X-, Y-, and, Z- axis were 0.93 cm, 1.81 cm and 1.08 cm respectively for SF-RT as compared to 0.58 cm, 1.01 cm, and 0.52 cm for CT-RT. Sites with maximum shift were extremity (X-axis, 4.3 cm), spine (Y-axis, 5.0 cm) and thorax, pelvis (Z-axis, 2.3 cm). There was a rising trend for the use of SF-RT with each passing year (0% in 2021 to 39.4% in 2024). Conclusion: In a high-burden, resource limited setting that prevails in majority of LMIC, SF-RT can help in providing timely radiation to palliative patients without a significant difference in set-up errors. SF-RT led to an average reduction of 0.5 days from scan import to first radiation along with reducing patient’s one hospital visits in Radiation Oncology department.

Keywords: Simulation Free Radiation, Palliative Radiation