3183 - Clinical Feasibility and Safety of 1.5 T MR-Guided Daily Adapted Radiotherapy in 1000 Patients: A Real-World Large Experience of an Early-Adopter Center
Presenter(s)
C. De-Colle1, M. Rigo1, A. Allegra2, L. D. Nicosia3, N. Giaj-Levra1, E. Pastorello1, F. Ricchetti1, C. Orsatti1, A. Romei1, N. Bianchi1, R. F. Borgese2, A. De Simone2, D. Gurrera1, S. Naccarato1, G. Sicignano1, R. Ruggieri2, and F. Alongi1,4; 1Department of Advanced Radiation Oncology, IRCSS "Sacro Cuore Don Calabria Hospital" Cancer Care Center, Negrar di Valpolicella (VR), Italy, 2Department of Advanced Radiation Oncology, IRCCS Sacro Cuore Don Calabria Hospital, Cancer Care Center, Negrar di Valpolicella, Italy, 3Department of Advanced Radiation Oncology, IRCCS "Sacro Cuore Don Calabria Hospital" Cancer Care Center, Negrar di Valpolicella (VR), Italy, 4University of Brescia, Brescia, Italy
Purpose/Objective(s):
The clinical implementation of MR-guided radiotherapy on MR-linacs (MRL) has rapidly increased in the recent years. The advantages represented by the MR-based daily online plan adaptation and real-time monitoring have been exploited for different tumor sites. Nevertheless, some concerns remain, mainly related to the longer treatment time and limited patient eligibility. We report here the experience of our center, where a 1.5T MRL was clinically implemented in 2019 and, since then, more than 1200 patients have been treated.Materials/Methods:
The first 1000 patients treated at the MRL in our department were selected. Technical information such as treatment time and adaptive technic have been prospectively recorded, while toxicity data were retrospectively collected.Results:
Between October 2019 and June 2024, 1000 patients for a total of 1061 treatment courses were included. Prostate and prostate bed were irradiated in 57.1% and 10.2% of the cases, respectively, including regional pelvic lymphnodes in 4.7%. Other frequent targets were lymphnodal metastases, pancreas and liver. The most frequent adopted doses were 36.25Gy (31%), 35Gy (28.3%) and 30Gy (9.4%) in 5 fractions. On a total of 9076 administered fractions, 80.8% were with adapt-to-shape and 19.2% with adapt-to-position method. The mean in-room time was 38 minutes (range, 18-103), with 74.4% of patients completing the session within 40 minutes. Acute grade (G) 3 toxicity was recorded in 1.6% of the cases, while, on a total of 858 patients available for late toxicity, G3 was recorded in 0.3% of the cases, with no >G3.Conclusion:
Our experience confirms that MRL treatments are feasible for different tumor entities in several anatomical sites. We showed that most of the patients could be treated within 40 minutes and showed low toxicity rates. Protocols for dose escalation and margin reduction, by adopting new comprehensive motion monitoring strategies, are under development.