ESTRO 2024 - Abstract Book

S3658

Physics - Dose prediction, optimisation and applications of photon and electron planning

ESTRO 2024

2382

Digital Poster

Analysis of the influence of gEUD biological optimization on auxiliary conformation structures

Alvaro Garcia Balsa 1 , Javier Sanchez Ruiperez 2 , Adrian Hierr Rivero 1 , Carlos Diaz Aviño 1 , zahara Martin Rodriguez 1 , Daniel San Jose Olmedo 1 , Alfonso Villace Gallego 1 , Daniel Rodriguez Latorre 1 , Silvia Fernandez Cerezo 1 , Diego Crelgo Alonso 1 , Pedro Sanchez Galiano 1 , Jose Fernandez Garcia 1 1 Hospital Universitario Central de Asturias, Fisica Medica, Oviedo, Spain. 2 Hospital Nuestra Señora de Sonsoles, Radioterapia, Avila, Spain

Purpose/Objective:

Over the years, the complexity of IMRT-VMAT treatments has increased considerably. In this work we investigate the biological optimization tool gEUD in conformal auxiliary structures (rings) with the aim to see its influence on the planning for its implementation in clinical practice.

Material/Methods:

To evaluate how biological optimization affects the treatments, plans are made using Eclipse15.6 (Varian) where a TrueBeam with an MLC120-Millenium has been modeled. The optimization algorithm used is PO.15.6.04 and the computational algorithm used is the AAA-v15.6. All plans have been made using two full 6MV arcs, normalized to the median.

The planning has been done simulating a fictitious homogeneous dummy of radius 10cm and length 40cm. A cylindrical PTV of radius 2.5cm and length 6cm has been contoured on it.

The generated rings have an inner radius at 1mm, 2mm, 5mm and 1cm from the PTV and a fixed outer radius at 2cm from it. For each ring the dose per fraction has been varied between 2Gy/fx, 5Gy/fx and 12Gy/fx and the values of the parameter "a" used in the optimization are 1, 5, 10, 20 and 40.

For each ring it has been optimized as follows:

- PTV: Lower-DVH D 100% =Dose Prescription ; Upper-DVH D 0% =Dose Prescription ; Priority=100.

- Ring: Upper-gEUD=25% of the Dose Prescription ; Priority=50

- NTO: automatic; Priority=50

No interaction is performed during the optimization process once the objectives are set.

To analyze the influence of these parameters, D 2% , D 10% , and D mean of the rings and D 98% , D 95% , D 2% of the PTV are evaluated.