Commissioning and validation of RayStation treatment planning system for CyberKnife M6

Abstract

Background RaySearch (AB, Stockholm) has released a module for CyberKnife (CK) planning within its RayStation (RS) treatment planning system (TPS). Purpose To create and validate beam models of fixed, Iris, and multileaf collimators (MLC) of the CK M6 for Monte Carlo (MC) and collapsed cone (CC) algorithms in the RS TPS. Methods Measurements needed for the creation of the beam models were performed in a water tank with a stereotactic PTW 60018 diode. Both CC and MC models were optimized in RS by minimizing the differences between the measured and computed profiles and percentage depth doses. The models were then validated by comparing dose from the plans created in RS with both single and multiple beams in different phantom conditions with the corresponding measured dose. Irregular field shapes and off‐axis beams were also tested for the MLC. Validation measurements were performed using an A1SL ionization chamber, EBT3 Gafchromic films, and a PTW 1000 SRS detector. Finally, patient‐specific QAs with gamma criteria of 3%/1 mm were performed for each model. Results The models were created in a straightforward manner with efficient tools available in RS. The differences between computed and measured doses were within ±1% for most of the configurations tested and reached a maximum of 3.2% for measurements at a depth of 19.5‐cm. With respect to all collimators and algorithms, the maximum averaged dose difference was 0.8% when considering absolute dose measurements on the central axis. The patient‐specific QAs led to a mean result of 98% of points fulfilling gamma criteria. Conclusions We created both CC and MC models for fixed, Iris, and MLC collimators in RS. The dose differences for all collimators and algorithms were within ±1%, except for depths larger than 9 cm. This allowed us to validate both models for clinical use.

Clinical application of a GPU-accelerated monte carlo dose verification for cyberknife M6 with Iris collimator

“…Previous clinical researchers have already explored some works for comparison of dose calculation in CK system, including the comparison with measured dose and the development of third-party dose verification tools. Gondré M et al [ 14 ] implemented the dose calculation of single beam in homogeneous and heterogeneous phantoms, multiple beams in homogenous and heterogeneous phantoms, and patient-specific dose verifications on clinical patients, the experimental results showed that the accuracy of MC model could fully meet clinical requirements. Heidorn SC et al [ 15 ] built a heterogeneous phantom with lung-equivalent material and solid water for dose calculation, which demonstrated the accuracy of MC algorithm was much higher than the accuracy of correction-based Finite-Size Pencil Beam (FSPB) algorithm in low-density regions.…”

“…Numerous studies have demonstrated the accuracy of MC algorithm for CK system [ 11 , 14 – 17 ], whether it is inherent in TPS or proposed by researchers. However, the above MC dose calculations are based on CPU cores and the computational time is still very long.…”