Experimental platform for ultra-high dose rate FLASH irradiation of small animals using a clinical linear accelerator

Publication date: Available online 20 September 2016
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Emil Schüler, Stefania Trovati, Gregory King, Frederick Lartey, Marjan Rafat, Manuel Villegas, A. Joe Praxel, Billy W. Loo, Peter G. Maxim
Backgroundand Purpose: A key factor limiting the effectiveness of radiation therapy is normal tissue toxicity, and recent preclinical data shows that ultra-high dose rate irradiation (>50 Gy/s, "FLASH") potentially mitigates this effect. However, research in this field has so far been strongly limited by the availability of FLASH irradiators suitable for small animal experiments. We present a simple methodological approach for FLASH electron small animal irradiation with a clinically available LINAC.Material and MethodsWe investigated the FLASH irradiation potential of a Varian Clinac 21EX in both clinical mode and after tuning of the LINAC. We performed detailed FLUKA Monte Carlo and experimental dosimetric characterization at multiple experimental locations within the LINAC head.ResultsAverage dose rates of up to 74 Gy/s were achieved in clinical mode, while the dose rate after tuning exceeded 900 Gy/s. We obtained 220 Gy/s at 1 cm depth for a >4 cm field size with 90% homogeneity throughout a 2 cm thick volume.ConclusionsWe present an approach for using a clinical linear accelerator for FLASH irradiations. We obtained dose rates exceeding 200 Gy/s following simple tuning of the LINAC with excellent dosimetric properties for small animal experiments. This allows for increased availability of FLASH irradiation to the general research community.



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