Abstract: Gd₃（Al，Ga）₅O₁₂∶Ce （GAGG） scintillators， characterized by high density （6.63 g/cm³）， high light yield （>58 000 ph/MeV）， fast decay time （～90 ns）， and stable physicochemical properties， are promising candidates for high spatial resolution X-ray imaging scintillation screens. Determining the spatial resolution limit of the GAGG scintillation screen and approaching this limit cost-effectively is a significant yet challenging task. In this work， GAGG single crystals without co-doping and with Mg or Yb co-doping were grown by the Czochralski method. A series of GAGG scintillation screens were prepared by cutting and polishing， and their optical and scintillation properties were systematically characterized. The theoretical spatial resolution was calculated via Geant4 simulations， and imaging experiments were conducted at the BL13HB beamline of the Shanghai Synchrotron Radiation Facility （SSRF）. Experimental studies confirm that GAGG scintillation screens exhibit superior imaging performance in X-ray applications， particularly beneficial for medical imaging and industrial nondestructive inspection applications. The theoretical spatial resolution of GAGG scintillation screens is 0.4 μm， whereas our experiment attained 0.9 μm （555 lp/mm）， a performance level that aligns with current state-of-the-art systems in the field. Comparative analysis reveals that spatial resolution exhibits limited variation with screen thickness in the 0.3~1 mm range， but shows greater sensitivity to surface conditions and optical transmittance. Therefore， in fabricating high-resolution GAGG scintillation screens， excessive reduction in thickness below practical thresholds is unnecessary. Efforts should prioritize improving crystalline optical quality through growth process optimization （inclusion suppression） and polishing technique refinement （surface roughness control）.

Key words: GAGG∶Ce; garnet; scintillator; scintillation screen; X-ray imaging; spatial resolution