ESTRO 2024 - Abstract Book

S847

Clinical - CNS

ESTRO 2024

In arm-B, the mean SURVIVAL DURATION (in days) (mean ± SD) of patients was 239.7± 83.8.

Conclusion:

Radiological response was not significantly different in two Temozolomide schedules with concomitant chemo radiation for treatment of high-grade glioma.

Toxicities (acute and late) and survival were not significantly different in two different Temozolomide schedules with concomitant chemo-radiation for treatment of high-grade glioma.

THEREFORE WE RECOMMEND THE USE OF PRE-RADIATION TEMOZOLOMIDE ONLY IN CASES OF DELAY IN TENTATIVE INITIATION OF RADIATION OR IN CASES OF LACK OF MEDICAL FITNESS FOR RADIATION IMMEDIATELY.

Keywords: Grade IV brain tumor

1575

Digital Poster

sphericity as a guiding parameter for cone-based stereotactic radiosurgery planning

Tik Yan Nam 1 , Chung Hei Leung 1 , Yan Kit Wah 1 , Man Cheuk Ng 1,2

1 St. Teresa's Hospital, Oncology Centre, Hong Kong, Hong Kong. 2 The University of Hong Kong, Department of Clinical Oncology, Hong Kong, Hong Kong

Purpose/Objective:

Cone-based stereotactic radiosurgery (SRS) is renowned for its rapid dose falloff beyond the target volume, thereby effectively reducing radiation exposure to adjacent normal tissues. However, this approach may not be optimal for non-spherical targets, as the prescribed isodose volume may not conform precisely to the target volume. The primary objective of this study is to determine the sphericity of the target volume required to achieve a conformal cone-based SRS plan. In addition, a comparative analysis is conducted between cone-based and multi leaf collimator (MLC)-based SRS plans.

Material/Methods:

A retrospective analysis was conducted on twenty SRS cases for lung cancer patients with brain metastasis. The cases encompassed treatments performed between August 2018 and September 2023. Each case was planned using three different treatment techniques: cone-based, conformal arc, and RapidArc. Cone-based and conformal arc plans were calculated using iplan version 4.5.5 (BrainLAB AG, Feldkirchen, Germany), while RapidArc plans were calculated using Eclipse version 16.1 (Varian Medical System, Palo Alto, CA). All plans were configured for the TrueBeam linear accelerator version 2.7 (Varian Medical System, Palo Alto, CA), equipped with Varian Millennium