Performance evaluation of a flexible GAGG sheet for surface imaging of x-rays from computed tomography (CT) and linear accelerator (LINAC)

A flexible scintillator sheet made of Ce-doped Gd₃Al₂Ga₃O₁₂(GAGG) powder mixed with a two-part silicone adhesive enabled high-intensity imaging of proton beams on complex surfaces; however, its effectiveness for x-ray imaging remained unclear. To investigate this, we tested surface imaging with the GAGG sheet for both x-rays from computed tomography (CT) system and high-energy x-rays from linear accelerator (LINAC). For imaging of x-ray beam from CT system, we irradiated a flexible GAGG sheet with 140 kV x-rays, positioning it on a patient bed or curved surface of a cylindrical phantom. The resulting light emission on the GAGG sheet was captured by a CMOS camera. For LINAC x-ray imaging, we irradiated the GAGG sheet with 6 MV x-rays, setting it on a flat phantom or a human head phantom, and again captured the emitted light using a CMOS camera. In both CT and LINAC x-ray imaging, the light produced on the GAGG sheet was successfully captured at intervals as short as 100 ms, enabling real-time tracking of beams. The light output from CT x-rays was more than 50 times higher than that of plastic scintillator, while the light output from LINAC x-rays was 1.2 times higher. Given its adaptability to complex surfaces and high light emission for x-rays as well as real-time imaging capability, the flexible GAGG sheet shows potential for efficient surface beam imaging in both CT and LINAC x-ray applications.