The increasing interest in FLASH-RT has lead to the conversion of linear
accelerators to enable ultra-high dose rate (UHDR) beams for preclinical
research. Dosimetry hereof remains challenging with several crucial aspects
missing. This work shows the challenges for real-time 2D UHDR dosimetry, E
aims to present a solution in the context of preclinical irradiations in
non-homogeneous UHDR electron beams. An experimental camera-scintillation sheet
combination, was used to investigate the spatial dose distribution of a
converted UHDR Varian Trilogy. The dosimetric system was characterized by
variation of the number of pulses and source to surface distance (SSD) and its
application was investigated by variation of bolus thickness and ambient light
intensity. The challenges of prelcinical real time 2D dosimetry with
scintillating coatings were assessed by ex vivo irradiations of a rat brain,
mouse hindlimb and whole body mouse. Radiochromic EBT XD film was used as
passive reference dosimeter. The coating showed a linear response with the
number of pulses in the absence and presence of transparent bolus, up to 3 cm
thick, and with the inverse squared SSD. The presence of ambient light reduces
the signal-background ratio. The sheet showed to have sufficient flexibility to
be molded on the subjects’ surface, following its curvatures. Linearity with
number of pulses was preserved in a preclinical setting. For small field sizes
the light output became too low, resulting in noisy dose maps. The system
showed robust within 5% for camera set up differences. Calibration of the
system was complicated due to set up variations and the inhomogeneity of the
beam. We showed the need for 2D real-time dosimetry to determine beam
characteristics in non-homogeneous UHDR beams using a preclinical setting. Noi
presented one solution to meet this need with scintillating based dosimetry.

Questo articolo esplora i giri e le loro implicazioni.

Scarica PDF: