ESTRO 2022 - Abstract Book

S200

Abstract book

ESTRO 2022

Figure 1: Reconstructed doses for the depicted motion trace with amplitude variation and baseline drift. Only MP4DRT fully restores target coverage.

Figure 2: Top: Overlay of planned doses (background) and measurement of the IC array (small squares) for MP4DRT. Bottom: Dependence of gamma (3%/3mm) pass rate between planned and measured dose distribution and of target D95 on the noise added to the motion signal for MP4DRT. Conclusion We showed in a clinical setting that MP4DRT is able to deliver highly conformal and homogeneous dose distributions to irregularly moving targets, even in the presence of clinically relevant imaging errors.

Poster Discussion: 06: CNS

PD-0239 Radiotherapy dose escalation in glioblastoma in the era of functional imaging: A prospective study

R. Madan 1 , C. draksham 1 , N. Kumar 1 , G. Trivedi 1 , A.K. Yadav 1 , M. Tripathi 2 , S. Goyal 1 , D. Khosla 1 , R. Basher 3 , C.K. Ahuja 4

1 Postgraduate Institute of Medical Education and Research, Radiotherapy and Oncology, Chandigarh, India; 2 Postgraduate Institute of Medical Education and Research, Neurosurgery, Chandigarh, India; 3 Postgraduate Institute of Medical Education and Research, Nuclear medicine, Chandigarh, India; 4 Postgraduate Institute of Medical Education and Research, Radiodiagnosis and Imaging, Chandigarh, India Purpose or Objective Local failure remains the major concern in glioblastoma (GBM) despite aggressive treatment. Pilot studies have shown that escalated radiotherapy (RT) dose beyond 60 Gy improves outcome in GBM, although the conclusive data is lacking. Here we present our preliminary data of RT dose escalation using pentixafor PET scan. High 68 Ga-pentixafor uptake is seen in glioma patients expressing chemokine receptor-4 which helps in sharp demarcation between normal brain and glioma cells. Materials and Methods The prospective study was conducted over a period of 18 months from March 2018 to December 2019. Post-operatively, all GBM patients underwent MRI brain and pentixafor PET scan. A delayed contrast enhanced planning CT scan was co- registered with MRI and PET. RT was planned in 2 phases. Phase 1 GTV (GTV1) comprised of T2/flair abnormality, PET avid disease and post-op cavity. A margin of 2 cm was given to GTV1 for phase 1 CTV (CTV1), which was expanded for 0.5 cm to generate phase 1 PTV (PTV1). RT dose of 46Gy/23# was prescribed to PTV1. Phase 2 GTV (GTV2) consisted of CT/MRI contrast enhancing lesion, PET avid disease and post op cavity. A margin of 2 cm was given to GTV2 to create phase 2 CTV