ESTRO 2024 - Abstract Book

S2064

Clinical - Paediatric

ESTRO 2024

thigh and legs were used to cover the whole-body. Each isocenter of the upper part of the body had 2 off-set 6 MV VMAT arcs rotating through 360° while in the lower part of the body only one, was used. The width of the field was set to 40 cm and the field length restricted to a maximum of 20 cm with a 2 cm overlap region at the iso. The collimator was rotate to 90° for each of these off-set arcs. MU rate was set at 80 MU/min.

Results:

TBI process timing and dosimetric parameters for the target and normal tissue were analyzed. Minimum coverage dose of 95% of the PTV (D95%) resulted between 88% and 92% with a Dmax between 118% and 120%. Mean lung dose resulted between 7.5 Gy and 9.2 Gy. Each arch resulted in around 150-180 MU. TBI process timing resulted higher than a conventional 2-D treatment one, especially for the simulation and planning part that required around 40’ and 6 to 7 hours vs 20’ and 40’ in a 2-D conventional one, respectively. The total beam-on time was calculated around 20’ as for a 2D conventional TBI delivery.

Conclusion:

TBI plan using a 3D VMAT technique is safe and possible. Treatment’s position resulted more comfortable for treated patients. Despite a higher planning time, a 3D VMAT technique let to be more aware of the dose distribution leading to the possibility to compare TBI treatments also from different Institutions. Daily IGRT ensure a higher accuracy in the patient’s re-positioning.

Keywords: Total body irradiation, VMAT, dose distribution

References:

1 J Clin Oncol 39:295-307. © 2020 by American Society of Clinical Oncology

3032

Digital Poster

Challenges in the treatment of pediatric patients undergoing total body irradiation.

Usha R Abraham 1 , Mathew D Hall 1,2 , Alonso Gutierrez 1 , Ranjini Tolakanahalli 1

1 Miami Cancer Institute, Radiation Oncology, Miami, USA. 2 Herbert Wertheim College of Medicine, Radiation Oncology, Mami, USA

Purpose/Objective:

The dosimetric outcome of IMRT plans on the Helical Tomotherapy for a cohort of 7 patients from ages of 1- 8 years and challenges involved in treatment.

Material/Methods: