ESTRO meets Asia 2024 - Abstract Book

S392

RTT – Treatment planning, OAR and target definitions

ESTRO meets Asia 2024

The new tools that avoid irradiating the prosthesis are essential for managing such patients, specifically the "Avoidance Structures" tool. Although Plans 3 and 4 achieve similar PTV coverage, optimization with "no entry" is favored due to slightly better results and reduced radiation passing through the prosthesis compared to the initial unrestricted plan. The "No entry+exit" option has been discarded from all plans, and it is suggested to investigate for which pathologies this optimization option of Eclipse could be useful.

Keywords: Planning Strategies, Prostheses, Radiotherapy

References:

[1]“A Dosimetric Comparison Using Avoidance Sectors vs Avoidance Structures for Hip Prostheses in Cancer Patients Receiving Pelvic Irradiation”. Grace E.

[2]“Evaluation of VMAT Planning Strategies for Prostate Patients with Bilateral Hip Prosthesis”. To D. et al.

[3]“Radiotherapy-induced toxicity in prostate cancer patients with hip prostheses”. Fischer A.

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Digital Poster

Dosimetric comparison of external beam radiotherapy treatment plans using VMAT optimization tools

CARMEN GIL LOPEZ

Radiofisica, Hospital Son Espases, Palma de Mallorca, Spain

Purpose/Objective:

Volumetric Modulated Arc Therapy (VMAT) is currently one of the most common techniques for cancer patients undergoing external beam radiotherapy due to its multiple advantages and good dose conformity. When planning a treatment, it is necessary to consider the dose delivered to organs adjacent to the tumor and minimize it. Different dose optimization tools can be used for this purpose, such as exclusion segments (which allow selecting the range of angles to avoid irradiation) and "Avoidance Structures" (which prevent the radiation beam from entering through a specific organ of interest or from entering and exiting through it). This study compares these optimization tools for bilateral breast cancer in 20 patients, evaluating the dose received by the lungs and heart while ensuring that the tumor (PTV) receives the prescribed dose in a homogeneous and conformal manner.

Material/Methods:

The Eclipse® version 13.6 treatment planning system from Varian Inc. was utilized, along with a Varian Clinac DHX 2100 linear accelerator and optimization tools such as exclusion segments and "Avoidance Structures".

Four plans were created with different planning strategies:

- Plan_1: No restriction.