ESTRO 2024 - Abstract Book

S3492

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

ESTRO 2024

39. Civco Medical Solutions CIVCO RT Technical Data Sheet - Type-STM Overlays, including FixatorTM Shoulder Suppression. [Internet] Civco RT; 2023 [cited 2023 May 06]. Available from https://civcort.com/ro/resources/Technical-Spec-Sheets/Type-S-Overlays-Technical-Data-Sheet_2023C1647_A.pdf

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Digital Poster

A dosimetrical assessment of MCO approach on organs at risk sparing in the VMAT of Brain Tumors

Nasim Amiri 1 , Bijan Hashemi 1 , Mohsen Bakhshandeh 2 , Amin Banaei 1

1 Tarbiat Modares University, Medical Physics, Tehran, Iran, Islamic Republic of. 2 Shahid Beheshti University of Medical Sciences, Radiology Technology, Tehran, Iran, Islamic Republic of

Purpose/Objective:

Modulated radiotherapy techniques such as volumetric modulated arc therapy (VMAT) need optimization to produce modulated irradiation. However, there can be various modulated plans to produce favorable dose distributions. Multi-criteria optimization (MCO) can provide several treatment plans with different dose distributions satisfying the clinical goals and dose objectives. Although some of the dosimetric parameters may be improved in a treatment plan and some may worsen compared to other provided plans. Therefore, it’s necessary to compare them and choose one of the provided plans. This study aimed to assess the dosimetrical results of VMAT treatment plans produced by MCO methods with the conventional VMAT without MCO to determine the effect of MCO on organs at risk (OARs) sparing and target dose homogeneity.

Material/Methods:

CT images and contoured structures of 34 patients with glioma brain tumor were considered, and conventional VMAT planning as well as MCO planning were performed on these data using the Raystation treatment planning system (Ver. 8A, RaySearch, Sweden). Three MCO-VMAT plans were considered for the comparison and analysis, including treatment plans with high, moderate and low priority for OARs sparing. The dosimetric parameters, including the maximum dose of OARs and target dose homogeneity and conformity, were analyzed and compared using descriptive statistics, Friedman, and Wilcoxon tests.

Results:

Our findings showed that conventional VMAT and MCO-VMAT plans had relatively similar homogeneity and conformity indices (HI and CI) (P>0.07). MCO-VMAT plans can significantly decrease the maximum dose of several organs, including the chiasm, brain stem, optic nerves, pituitary gland and cochlea (P<0.05). However, the VMAT MCO plans do not significantly improve the dose sparing of some OARS, such as lens maximum dose and mean dose of eye globes and hippocamps (P>0.06). MCO plans with the higher priority of OARs sparing resulted in significantly higher OARs dose reduction while not significantly worsening target tissue homogeneity.

Conclusion: