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Experimental characterization of plastic scintillators at flash regime.
Cavalieri A., Bisogni M.G., Ciarrocchi E., Del Sarto D., Di Martino F., Massa M., Moggi A., Morrocchi M., Pensavalle J.H., Ravera E.
FLASH radiotherapy shows a higher healthy tissues sparing compared to the conventional radiotherapy. To obtain the so-called FLASH effect the dose rate must be higher than 40 Gy/s and a dose of at least 10 Gy must be delivered in less than 200 ms. For electron LINAC pulsed beams, the FLASH conditions cause saturation in standard ion chambers. Thanks to their fast decay times (ns), we have proposed plastic scintillators as online dosimeters for FLASH beams. We studied two scintillating fibers of different volumes and emission spectra (a blue fiber with emission peak at 450 nm and a green one with peak at 530 nm). The measures were made using the ElectronFlash LINAC located at the Centro Pisano per la Flash Radiotherapy (CPFR) in Santa Chiara University Hospital. The signal emitted by the scintillating fibers was read by a CCD. To evaluate the saturation, we increased the dose per pulse reaching values higher than 20 Gy per pulse. A linear response was observed for both fibers for dose per pulse up to 15 Gy and a modest saturation at 20 Gy that can be corrected with calibration.