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Commissioning of 45 MV Racetrack Microtron for Radiodynamic Therapy

A Eldib*, J Liu , J Xu , J Panetta , T Lin , R Price , C Ma , Fox Chase Cancer Center, Philadelphia, PA


(Monday, 7/15/2019) 3:45 PM - 4:15 PM

Room: Exhibit Hall | Forum 3

Purpose: Radio-dynamic therapy is a novel treatment technique that combines high-energy photon beams and photo/radio-sensitizers to target tumors. Preliminary results from clinical trials for late-stage cancer patients showed encouraging clinical outcome. A Top Grade LA45 Racetrack Microtron has been installed in our department. This paper reports the acceptance testing and commissioning results for this system.

Methods: A Racetrack Microtron combines the principles of both a linear accelerator and a cyclotron to produce high energy photon and electron beams. The current system can produce 45 MV photon beams designed for radio-dynamic therapy. The LA45 vault is subdivided into two sections: the treatment room and the accelerator room. The treatment room houses the gantry and the patient couch while the accelerator room houses the Microtron accelerator. Radiation survey measurements were performed in all areas surrounding the LA45 vault. In addition we also mapped the direction of leakage radiation during the acceleration process. The machine was accepted and commissioned based on the requirements for radio-dynamic treatments. The beams were calibrated in water with a NIST traceable farmer chamber following the AAPM TG51 report. Both the Top Grade TPS and Varian Eclipse were commissioned for radio-dynamic therapy treatment planning.

Results: Radiation survey results met the designed 2mrem/week for the public and 10mrem/week for radiation workers in all areas surrounding the accelerator and treatment rooms. The relative accelerator head leakage did not exceed the maximum allowed leakage of 0.1%. Beam characteristics were studied through measurements of various profiles and depth dose curves for different field sizes. The depth of maximum dose under reference conditions was 4.7 cm and the beam quality specified by the percentage dose at 10cm depth was 91.6%.

Conclusion: The LA45 Racetrack accelerator has been accepted and commissioned for patient treatment following a phase I radio-dynamic therapy clinical trial.


Commissioning, Microtrons, Shielding


TH- External beam- photons: Development (new technology and techniques)

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