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 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 µm at a distance of 250 µm working distance, or 4.9 µm and 32.5 µm 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 non-destructive characterization