1. Clinical Experience Using the SRS MapCHECK for Patient Specific Plan Verification of Flattening Filter Free, Non-Coplanar Stereotactic Brain Plans Using HyperARC
- Author
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Ashburner M and Mugabe K
- Subjects
Flattening filter free ,Computer science ,business.industry ,Computer vision ,Plan (drawing) ,Artificial intelligence ,Patient specific ,business ,Non coplanar - Abstract
HyperArc (HA) treatment planning from Varian is a stereotactic specific planning tool enabling quick and efficient optimisation of treatment planning, and delivery. HA was commissioned and implemented at Waikato Regional Cancer Centre (WRCC) in 2019 to fulfil the demands of dose delivery for stereotactic radiosurgery (SRS), allowing for treatment of multiple targets with a single isocenter at non-coplanar angles. The extra levels of plan complexity involved in creating and verifying HA SRS plans required extensive checks and verifications using film and an ion chamber, along with a significant allocation of time and resources. The Sun Nuclear SRS MapCHECK (SRSMC) offered an alternative to the cumbersome film measurements. It is an all-encompassing tool meeting the requirements of TG 218 and ICRU 91 for complex treatment plan verification, claiming to save time and effort, without sacrificing accuracy, enabling for a smoother planning and verification process. SRSMC was initially commissioned on 6MV single target treatments using standard planning, then updated and commissioned for 6FFF multi-target non-coplanar treatments using HA. The SRSMC gamma pass rates were compared to film measurements in the same plane, and the central diode CAX reading compared to ionisation chamber measurements at the same position for a range of plans covering a range of PTV sizes and plan complexities. Pass rates on the SRSMC were comparable to measurements using film (Gamma 3%/1mm, 99.41%, 96.39% SRSMC and film respectively). The central diode is an adequate surrogate for a chamber measurement if the SRSMC is positioned in a similar position as that of the ionisation chamber would be – high dose homogenous region, avoiding steep gradients (mean dose difference Diode vs Chamber: -0.73%). Differences between exposing non-coplanar plans at couch 0 and at planned couch angles were negligible (Gamma 3%/1mm 99.28 coplanar, 99.41% non-coplanar on SRSMC). At WRCC the SRSMC has replaced film and chamber measurements for plan verifications of 6FFF HA multiple metastatic brain treatments at a single isocenter and we are currently investigating its use in other treatment sites.
- Published
- 2021