(Sunday, 7/29/2018) 3:00 PM - 6:00 PM
Room: Exhibit Hall
Purpose: To commission Brainlab iPlan- and Elements-based stereotactic radiosurgery (SRS) utilizing both MLC and Aktina cone solutions on an Elekta Agility platform, particularly as integration of Brainlab SRS on Agility machines has not been previously supported.
Methods: Commissioning measurements were acquired as specified in the Brainlab Physics Technical Reference Guide. Measurements were taken using an IBA Blue Phantom 2 scanning tank, SNC Edge diode, and various ion chambers (Welhofer CC13, CC01; PTW N30013). GAFchromic EBT3 film and the Elekta iView EPID were also utilized. Validation included end-to-end testing using in-house phantoms and the Radiological Physics Center’s (RPC) SRS head phantom. End-to-end testing allowed for critical workflow commissioning of this new Brainlab/Elekta integration.
Results: We chose to utilize only the 6 FFF beam clinically for both MLC- and cone-based SRS. Our MLC-shaped beam yielded 0.3% leakage (both open- and closed-jaw). At 100 mm, the PDD for 10, 20, and 30 mm square fields was 58.9%, 61.3%, and 62.8%, respectively. Output factors for 10, 20, and 30 mm square fields were 0.7319, 0.8366, and 0.8736, respectively. For 5, 7, and 10 mm circular cones, Brainlab-defined scatter factors were 1.023, 1.173, and 1.289 with PDDs at 100 mm depth of 55.7%, 57.0%, and 58.2%, respectively. RPC SRS head irradiation yielded a dose to the center of the target ratio of 0.96 (Criteria: 0.95-1.05) and film plane Gamma passing of 97% (coronal) and 95% (sagittal) (Criteria: ≥85% for both). RPC phantom irradiation using circular cones is pending, as is final release of Brainlab-planned Aktina cone-based SRS by Elekta. Commissioning also revealed inadequate documentation of some required measurements along with several workflow concerns and communications issues, which are being addressed by Brainlab.
Conclusion: Final validation of Brainlab SRS on our Elekta Agility verified feasible integration suitable for safe and reliable patient treatment.
Keywords
Commissioning, Small Fields, Stereotactic Radiosurgery
Taxonomy
TH- External beam- photons: intracranial stereotactic/SBRT
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