Geometrical Characterization of an Inorganic Scintillator Detector for Proton Therapy Using a Micrometer-Scale Ion Beam

The fabrication process of an inorganic scintillator detector (ISD), grafted at the tip of an optical fiber, is currently under optimization for its application in proton therapy in vivo dosimetry. The detector signal magnitude under proton irradiation is strongly correlated to the geometry of the detector-sensitive head and must be accurately characterized. This parameter is also essential for detector response calculation using the Monte Carlo (MC) simulation. The purpose of this work is to get a luminescence map of the ISD scanned with a 4-MeV H+ microbeam. The beam is tightly focused on a spot with a diameter of
$2.2~\mu $
m at a distance of 250-
$\mu $
m working distance, or 4.9 and
$32.5~\mu $
m at distances of 1 and 4 mm, respectively. The beam scans the detector in a raster scan mode. The luminescence signal emitted locally by the detector is collected via the optical fiber and measured using a photon counter. The results provide insights into the geometry of the efficient volume of the detector without damage, making this technique particularly suitable for nondestructive characterization.