2244 - Verification of GammaTile Plans Generated by MIM Symphony Software Using Monte Carlo Simulation
Presenter(s)
A. Tiwari1, M. Aryal1, K. Huang1, O. M. Oderinde2, S. K. Ng1, D. Campos3, Y. Yue1, and C. F. Njeh1; 1Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN, 2Advanced Molecular Imaging in Radiotherapy (AdMIRe) Research Laboratory, School of Health Sciences, Purdue University, West Lafayette, IN, 3Indiana University Health, Indianapolis, IN, United States
Purpose/Objective(s): Our clinic employs MIM Symphony Software to create GammaTile treatment plans for post-operative radiation therapy. However, to our knowledge, Monte Carlo (MC) verification of this planning system has not been documented in the literature. This study aims to assess the dosimetric accuracy of MIM-generated GammaTile plans using MC simulations.
Materials/Methods: Dose distributions from GammaTile implants using Cs-131 seeds were simulated using the TOPAS Monte Carlo toolkit. A solid water phantom measuring 16 × 16 × 16 cm³ was scanned by CT and the GammaTile measuring 2 × 2 × 0.4 cm³, contained four Cs-131 seeds was placed in the phantom. The plan was created in MIM Symphony to deliver 30 Gy, which was replicated in the MC simulation. The geometry of the Cs-131 seeds and the GammaTile matrix was fully integrated into the MC model for dose calculations. A volumetric radionuclide ion source was utilized to ensure accurate dose simulations. To reduce computation time, parallel processing with 24 processors on a dedicated Linux machine was employed. The resulting 3D dose distributions and 1D dose profiles from the MC simulation were compared with the dose distributions generated by MIM Symphony.
Results: The dose distributions from the MC simulations agreed with those from the MIM-generated plan within 3% overall. Differences were primarily noted in the dose fall-off regions near the Cs-131 seeds. In regions with minimal dose variation, the agreement was within 0.5% to 1%, while larger discrepancies of 1% to 3% were observed in areas with steep dose gradients.
Conclusion: Our findings provide external verification that MIM Symphony-generated GammaTile treatment plans are dosimetrically accurate within acceptable limits. Future work should investigate the impact of homogeneity corrections in cases where the disease is located closer to the skull.