A Palmiero*, A Glick, K Liu, N Chopra, D Neill, S Massia, E Schueler, S Beddar, UT MD Anderson Cancer Center, Houston, TX

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  A Palmiero

PO-GePV-T-66 (Sunday, 7/10/2022)   [Eastern Time (GMT-4)]

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Purpose: FLASH radiation therapy at dose rates ≥40Gy/s induces a normal tissue sparing affect while maintaining tumor kill (termed FLASH effect). The FLASH Mobetron unit commercialized by IntraOp Medical has recently been introduced to the market with FLASH capabilities producing 9 and 6MeV electron beams with dose rates up to 1000Gy/s. The purpose of this study was to evaluate the short and long term stability for the FLASH Mobetron in preparation for clinical implementation.

Methods: The 9MeV conventional beam along with the 6 and 9MeV FLASH beams are being evaluated for beam stability. This consists of daily output and energy measurements over several weeks (short-term stability) to several months (long-term stability). Weekly percent depth dose curves are also taken and analyzed using an in-house developed film water tank. These measurements are validated using a multi-detector approach utilizing a Markus chamber, Gafchromic film and toroid sensor data. Stability of dose output per MU for the conventional beam and per pulse for the FLASH beams are also considered as well as stability in flatness and symmetry of all the beam energies.

Results: Our initial results show that daily output variation was within 2% for the 9MeV conventional beam and 3% for the 9 MeV FLASH beam. Maximum standard deviation was less than 1% for the conventional beam and 1.5% for the flash beam. The average R50 for the conventional beam was found to be 4.11cm and 4.13cm for the FLASH beam. Correlation between toroid sensor, film and Markus chamber data is apparent.

Conclusion: The FLASH Mobetron is one of the first commercial FLASH systems available for pre-clinical and clinical translational use. Our initial measurements of the FLASH Mobetron show a high reliability in terms of output and energy stability, in line with published AAPM reports for similar units producing conventional dose rates.

Keywords

Electron Therapy, Quality Assurance, FLASH Radiotherapy

Taxonomy

TH- External Beam- Electrons: Quality Assurance - Linear accelerator

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