ESTRO 2025 - Abstract Book

S4145

RTT - Patient care, preparation, immobilisation and IGRT verification protocols

ESTRO 2025

4378

Digital Poster Integrating Gentle IGRT into Routine Pediatric Radiotherapy: A Step Toward Safer and More Efficient Clinical Practice Lucrezia Bernabucci 1 , Gerardina Stimato 2 , Veronica Pollutri 1 , Elisa Mendolesi 1 , Chiara Elia 1 , Sara Iacovone 1 , Silvia Mariani 1 , Elisa Marconi 1 , Noemi Marchionne 1 , Mariangela Massaccesi 1 , Giuseppe Nicolì 1 , Antonio Ruggiero 3,4 , Angela Mastronuzzi 5 , Patrizia Cornacchione 1 , Gabriele Turco 1 , Vincenzo Frascino 1 , Luca Indovina 1 , Marco De Spirito 1,6 , Luca Tagliaferri 1,7 , Maria Antonietta Gambacorta 1,7 , Silvia Chiesa 1 1 UOC di Radioterapia Oncologica, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Roma, Italy. 2 U.O.S.D. Fisica Medica e Radioprotezione, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Roma, Italy. 3 Pediatric Oncology Unit, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy. 4 Department of Woman and Child Health and Public Health, Università Cattolica del Sacro Cuore, Rome, Italy. 5 Department of Onco-Hematology, Cell Therapy, Gene Therapies and Hemopoietic Transplant, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy. 6 Dipartimento di Neuroscienze, Sezione di Fisica, Università Cattolica del Sacro Cuore, Roma, Italy. 7 Istituto di Radiologia, Università Cattolica del Sacro Cuore, Roma, Italy Purpose/Objective: In pediatric oncology, improving survival rates necessitates focusing on long-term effects, including the consequences of radiation exposure. Modern radiotherapy technologies allow for highly conformal dose delivery, minimizing damage to healthy tissues. However, precise dose delivery, requiring the integration of Image-Guided Radiation Therapy (IGRT), contributes to cumulative radiation exposure. This is particularly concerning in pediatric patients, whose developing tissues are more sensitive to radiation and face greater risks of long-term sequelae. The Varian "Gentle IGRT" approach strives to balance precise targeting with minimized imaging doses, as demonstrated in our preliminary experience with its implementation in pediatric radiotherapy. Material/Methods: Since June 2024, our radiotherapy division has applied the gentle IGRT protocol to all pediatric patients. This protocol includes reduced kV (80) and mAs (100) settings, CTDIvol (0.94 mGy), and PDL (17.4 mGy*cm). It was used for all pediatric patients requiring CBCT (Cone Beam Computed Tomography) for precise treatments, often necessitating multiple CBCTs per day depending on the number of isocenters. Three treatment types were considered: brain, abdomen, and craniospinal axis. The Effective Dose (ED) from CBCT acquisitions during treatment was calculated using the formula: ED = PDL * k, where k is derived from ICRP 103, based on the patient’s age and anatomical region. Results: CBCT was performed on 23 pediatric patients, image quality was consistently sufficient, with no need for CBCT repetition or filter adjustments. The average time for IGRT, including acquisition, validation, and shift application, was 2 minutes and 25 seconds, indicating that the gentle IGRT protocol fits into routine clinical workflows. The estimated ED from CBCT acquisitions for the entire treatment course were: · Brain: 2.1 mSv · Abdomen: 21.9 mSv · Craniospinal axis: 22.8 mSv (1.1 mSv for brain, 13.3 mSv for dorsal spine, 8.3 mSv for lumbar spine). These doses were lower than those from traditional IGRT protocols, demonstrating the effectiveness of the gentle IGRT approach in reducing radiation exposure while maintaining image quality. Conclusion: Our preliminary results demonstrate that the gentle IGRT protocol is feasible in daily pediatric radiotherapy workflows. It balances reduced imaging doses with adequate image quality and minimal time delays. Ongoing prospective studies aim to quantify CBCT dose contributions using the image gently filter and compare them to