ESTRO 2023 - Abstract Book

S919

Digital Posters

ESTRO 2023

PFS and OS (p<0.001). By way of splitting the cohort in 3 groups based on their average brain dose; low dose (bottom 25% percentile), medium (25-75% percentile) and high dose (top 25% percentile), it is apparent that both the progression-free survival is dramatically impacted. Potentially, either average dose to the brain (or dose to the brainstem) might be suited for prognostication as compared to other clinical prognostic factors.

Conclusion The superior PFS and OS outcomes for PT indicates that the tumor and characteristic-based treatment modality selection process is beneficial for the patients, though average brain dose may be better suited for this purpose. There was no difference in PsP for XRT and PT. PT was associated with lower rates of fatigue <3 months after RT.

PO-1149 Factors influencing set up margins for image guided frameless stereotactic radiosurgery

R. Talukdar 1 , A. Dasgupta 1 , A. Chatterjee 1 , A. Mishra 1 , O. Roy Chowdhury 2 , K.J. Joshi 3 , A. Sutar 3 , J. Sastri Goda 1 , R. Krishnamurthy 1 , T. Wadasadawala 1 , R. Pathak 1 , P. Maitre 1 , V. Murthy 1 , A. Gupta 1 , P. Mittal 1 , S. Chopra 1 , A. Tibdewal 1 , N. Mummudi 1 , V. Singh 4 , P. Shetty 4 , A. Moiyadi 4 , R. Kinhikar 3 , R. Sarin 1 , J. Agarwal 1 , T. Gupta 1 1 Tata Memorial Centre, Homi Bhabha National Institute (HBNI), Radiation Oncology, Mumbai, India; 2 Tata Memorial Centre, Homi Bhabha National Institute (HBNI), Biostatistics, Mumbai, India; 3 Tata Memorial Centre, Homi Bhabha National Institute (HBNI), Medical Physics, Mumbai, India; 4 Tata Memorial Centre, Homi Bhabha National Institute (HBNI), Neurosurgery, Mumbai, India Purpose or Objective The introduction of frameless stereotactic immobilization device has improved patient compliance and enabled the delivery of fractionated stereotactic radiosurgery (SRS). With several variants of immobilization devices available for clinical use, the practice is often variable, using different planning target (PTV) margins. The current study evaluated setup accuracy for linear accelerator (LINAC) based SRS.

Materials and Methods