ESTRO meets Asia 2024 - Abstract Book

S339

Physics – Quality assurance and auditing

ESTRO meets Asia 2024

41

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Dose prescription and reporting in stereotactic radiosurgery: a single institution study

Egor Borzov, Tomer Charas, Salem Billan, Raquel Bar-Deroma

Oncology, Rambam, Haifa, Israel

Purpose/Objective:

This study aimed to evaluate the dosimetric variability in SBRT/SRS treatments, looking at different disease sites and individual planning strategies. This data, besides providing a critical view on our particular radiation department guidelines, may be used for inter-institutional comparison and enrich data driving standardization.

Material/Methods:

A single institution retrospective analysis was performed. The clinical SBRT/SRS plans that were used for patient radiotherapy were gathered for this study. All plans were planned with Monaco (Elekta AB, Sweden) treatment planning system (TPS) using a 2 mm spatial grid and a Monte Carlo dose calculation algorithm. The treatments were delivered on an Elekta Versa HD linear accelerator with a 6 FFF photon beam. For each plan, the dosimetric parameters D (0.1cc), D 50 , D 95 , D 99 were recorded in order to represent near-maximum dose, mean dose, 95% volume coverage, and 99% volume coverage as a near-minimum dose, respectively. Additionally, homogeneity index (HI) and conformity index (CI) were calculated. HI was calculated as the difference between D 99 and D(0.1cc) divided by D 50, and CI exactly following ICRU-91 recommendation. In all calculations the 100% isodose level was set to be the prescription dose per fraction as defined in the Record and Verify System (MOSAIQ). Furthermore, radiation medical physicist (RMP) and an attending radiation oncologist (RO) were attributed for each case.

Results: