ESTRO 2025 - Abstract Book

S899

Clinical - Haematology

ESTRO 2025

Conclusion: Interestingly, the IPS incidence rates in our cohort (without lung shielding) align with existing literature (with lung shielding). However, IPS is not the only acute pulmonary toxicity following hematopoietic stem cell transplantation. To account for other serious pulmonary toxicities, we reported acute hypoxemia (AH) rates, providing a broader view of treatment-related risks. This article aims to discourage treatment comparisons based solely on IPS (or intersitial pneumonitis) rates.

Keywords: Total Body Irradiation, Lung shielding, IPS

References: Wenger DS, Triplette M, Crothers K, et al. Incidence, Risk Factors, and Outcomes of Idiopathic Pneumonia Syndrome after Allogeneic Hematopoietic Cell Transplantation. Biol Blood Marrow Transplant . 2020;26(2):413-420. doi:10.1016/J.BBMT.2019.09.034 Fukuda T, Hackman RC, Guthrie KA, et al. Risks and outcomes of idiopathic pneumonia syndrome after nonmyeloablative and conventional conditioning regimens for allogeneic hematopoietic stem cell transplantation. Blood . 2003;102(8):2777-2785. doi:10.1182/BLOOD-2003-05-1597

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Digital Poster 2D TOTAL BODY IRRADIATION: THE END OF AN ERA AT OUR CENTER.

Celia Nicolás - Boluda 1 , José M. Álvarez - Pérez 2 , Pablo García - Jaén 3 , Adelaida Nieto - Palacios 1 , Pedro Soria - Carreras 1 , Julio A. Ramos - Pacho 2 , Orlanda Alonso - Rodríguez 1 , Lucía López - Corral 3 , Luis A. Pérez - Romasanta 1 1 Radiation Oncology, Hospital Universitario de Salamanca, Salamanca, Spain. 2 Physic and Radiation Protection, Hospital Universitario de Salamanca, Salamanca, Spain. 3 Haematology, Hospital Universitario de Salamanca, Salamanca, Spain Purpose/Objective: Total body irradiation (TBI) is often used as part of the conditioning regime for stem cell transplant (SCT). At our center, it has been traditionally delivered using 2-Dimensional (2D) techniques with a conventional linac (linear accelerator) using anterior-posterior (AP/PA) beam arrangements at extended source – to – surface distance (SSD). Upcoming 2025, we will move from 2D to 3D VMAT technique. We report on the patients treated in our institution the last 20 years with this technique. Material/Methods: We performed a single institution retrospective analysis of 97 patients with hematologic malignancies treated with TBI from July 2004 to February 2024. Patients were positioned lateral decubitus, specific parameters were determined in advance of treatment such as field size, monitor units, dose rate and shielding. Customized lung shielding blocks were made to reduce mean lung dose. Calculations were performed by the medical physicist to determine monitor units to achieve the prescribed dose. In vivo dosimetry with diodes was used to assess dose homogeneity. Patient and treatment characteristics, graft versus host disease (GVHD) and outcomes were evaluated. Kaplan-Meier in SPSS v 19.0 (IBM Corp) was used for statistical analyses. Results: Median age at TBI was 35 years (range 16 to 65 years), 63% males. Most relevant hematologic malignancies were acute lymphoblastic leukemia (ALL) Ph+ (n=41), ALL Ph– (n=8), ALL–T (n=17), acute myeloid leukemia (AML) (n=12), non-Hodgkin lymphoma (n=2), medullary aplasia (n=5) and myelodysplastic syndrome (n=3). Most patients (89%) underwent linac-based TBI, whilst 11% were treated in a Cobalt-60 unit (before 2008).