Feasibility, Treatment Planning, and Clinical Results of VMAT‐Based Total Body Irradiation for Pediatric Patients: Single‐Center Experience
Soraya Mico, Marcelino Hermida‐López, Mónica Ramos‐Albiac, Savannah Pié‐Padró, Pau Guardiola‐Zaragoza, Paula Navarro‐Palomas, Antonio Jurado, David García, Jordi GiraltABSTRACT
Background and Purpose
Total body irradiation (TBI) is a standard component of conditioning regimens for pediatric patients with acute lymphoblastic leukemia (ALL) undergoing hematopoietic stem cell transplantation (HSCT). Volumetric modulated arc therapy (VMAT) has emerged as a promising technique to improve dose conformity and organ‐at‐risk (OAR) sparing. This study evaluates the feasibility, dosimetric performance, and acute toxicity of a VMAT‐based TBI (VMAT‐TBI) technique implemented in a pediatric population.
Materials and Methods
Fifteen pediatric patients treated with myeloablative VMAT‐TBI between August 2019 and December 2024 were retrospectively analyzed. Prescription regimens ranged from 9.9 to 12 Gy, delivered in three to six fractions. Planning objectives followed ESTRO–ACROP–SIOPE recommendations, with mean lung dose less than 8 Gy and mean kidney dose less than 10 Gy. Dosimetric coverage, OAR sparing, patient‐specific quality assurance, image‐guided verification, and clinical outcomes were assessed.
Results
All treatment plans achieved adequate target coverage (mean PTV D95% = 96.6% ± 2.5%), with V110% = 19.1% ± 11.2% and V120% less than 1%. Mean lung and kidney doses were 7.8 ± 0.7 and 8.9 ± 1.1 Gy, respectively. Planned and measured dose distributions showed excellent agreement (gamma passing rates with 3%/3 mm criteria of 96.2% ± 4.6% with ArcCHECK diode array). After a median follow‐up of 18 months, one late non‐infectious pulmonary toxicity and one severe renal toxicity were observed.
Conclusion
VMAT‐TBI is a feasible, effective technique for pediatric HSCT conditioning, providing excellent target coverage, OAR sparing, and acceptable toxicity. These findings support VMAT‐TBI as a viable alternative to conventional TBI.