Experimental Platform for Ultra-high Dose Rate FLASH Irradiation of Small Animals Using a Clinical Linear Accelerator

Purpose A key factor limiting the effectiveness of radiation therapy is normal tissue toxicity, and recent preclinical data have shown that ultra-high dose rate irradiation (>50 Gy/s, “FLASH”) potentially mitigates this effect. However, research in this field has been strongly limited by the avai...

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Bibliographic Details
Published in:	International journal of radiation oncology, biology, physics Vol. 97; no. 1; pp. 195 - 203
Main Authors:	Schüler, Emil, PhD, Trovati, Stefania, PhD, King, Gregory, PhD, Lartey, Frederick, PhD, Rafat, Marjan, PhD, Villegas, Manuel, Praxel, A. Joe, Loo, Billy W., MD, PhD, Maxim, Peter G., PhD
Format:	Journal Article
Language:	English
Published:	United States Elsevier Inc 01-01-2017
Subjects:	Abdomen - diagnostic imaging ANIMALS Calibration DOSE RATES DOSIMETRY Equipment Design - methods Film Dosimetry - methods GY RANGE 10-100 GY RANGE 100-1000 Hematology, Oncology and Palliative Medicine IRRADIATION LINEAR ACCELERATORS MONTE CARLO METHOD Organs at Risk - radiation effects Particle Accelerators - instrumentation Radiation Injuries, Experimental - prevention & control Radiology RADIOLOGY AND NUCLEAR MEDICINE Radiosurgery - instrumentation Radiosurgery - methods RADIOTHERAPY Radiotherapy Dosage Thorax - diagnostic imaging
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Summary:	Purpose A key factor limiting the effectiveness of radiation therapy is normal tissue toxicity, and recent preclinical data have shown that ultra-high dose rate irradiation (>50 Gy/s, “FLASH”) potentially mitigates this effect. However, research in this field has been strongly limited by the availability of FLASH irradiators suitable for small animal experiments. We present a simple methodologic approach for FLASH electron small animal irradiation with a clinically available linear accelerator (LINAC). Methods and Materials We 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. Results Average dose rates of ≤74 Gy/s were achieved in clinical mode, and 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. Conclusions We present an approach for using a clinical LINAC for FLASH irradiation. We obtained dose rates exceeding 200 Gy/s after simple tuning of the LINAC, with excellent dosimetric properties for small animal experiments. This will allow for increased availability of FLASH irradiation to the general research community.
ISSN:	0360-3016 1879-355X
DOI:	10.1016/j.ijrobp.2016.09.018