A novel method for measuring the backscatter factor on a curved surface for diagnostic X-rays using a flexible scintillator sheet.

The ESD is calculated using the backscatter factor (BSF). However, BSFs for flat surfaces have been used even though simulations have shown that the BSFs for curved surfaces, which represent the human body more accurately, do not match those for flat surfaces. Measuring these values in practice presents a challenge because conventional dosimeters used for BSF measurement have sensitive volumes that cannot conform to curved surfaces. In this study, we measured the BSF for a curved surface using a flexible scintillator. The scintillator, composed of Gd₃Al₂Ga₃O₁₂ (GAGG) scintillator powder mixed with a silicone adhesive, was securely attached to the curved surface of a cylindrical phantom. Diagnostic X-rays were irradiated onto the scintillator, and the BSFs were evaluated as the ratio of the light output with and without the phantom. We successfully measured BSFs on a curved surface using a flexible scintillator. The mean difference between the BSFs obtained from the experiments using the flexible scintillator and those obtained from the simulations for the cylindrical phantom was 0.43%. The maximum difference was 1.47%, which was observed at a tube voltage of 40 kV. Thus, the BSFs measured using the flexible scintillator agree well with the simulated results. Our scintillator is useful for measuring BSFs on curved surfaces and contributes to dose management.