title: Development of a Monte Carlo model for treatment planning dose verification of the Leksell Gamma Knife Perfexion radiosurgery system.
abstract: Detailed Monte Carlo (MC) modeling of the Leksell Gamma Knife (GK) Perfexion (PFX) collimator system is the only accurate ab initio approach appearing in the literature. As a different approach, in this work, we present a MC model based on film measurement. By adjusting the model parameters and fine-tuning the derived fluence map for each individual source to match the manufacturer's ring output factors, we created a reasonable virtual source model for MC simulations to verify treatment planning dose for the GK PFX radiosurgery system. The MC simulation model was commissioned by simple single shots. Dose profiles and both ring and collimator output factors were compared with the treatment planning system (TPS). Good agreement was achieved for dose profiles especially for the region of plateau (< 2%), while larger difference (< 5%) came from the penumbra region. The maximum difference of the calculated output factor was within 0.7%. The model was further validated by a clinical test case. Good agreement was obtained. The DVHs for brainstem and the skull were almost identical and, for the target, the volume covered by the prescription (12.5 Gy to 50% isodose line) was 95.6% from MC calculation versus 100% from the TPS.
authors.affiliation: University Hospitals, Case Medical Center. jiankui.yuan@uhhospitals.org.
authors.forename: Jiankui
authors.initials: J
authors.lastname: Yuan
authors.forename: Simon S
authors.initials: SS
authors.lastname: Lo
authors.forename: Yiran
authors.initials: Y
authors.lastname: Zheng
authors.forename: Jason W
authors.initials: JW
authors.lastname: Sohn
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Sloan
authors.forename: Rodney
authors.initials: R
authors.lastname: Ellis
authors.forename: Mitchell
authors.initials: M
authors.lastname: Machtay
authors.forename: Barry
authors.initials: B
authors.lastname: Wessels
mesh_terms: D000465:Algorithms; D001932:Brain Neoplasms / Q000601:surgery*; D001933:Brain Stem / Q000528:radiation effects; D006801:Humans; D008962:Models, Theoretical; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D016634:Radiosurgery / Q000295:instrumentation* / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012886:Skull / Q000528:radiation effects