A phosphor screen comprises an inorganic phosphor capable of absorbing X-rays and emitting electromagnetic radiation having a wavelength greater than 300 nm. The phosphor is disposed on a support that has a reflective substrate comprising a continuous polyester first phase and a second phase dispersed within the continuous polyester first phase. The second phase contains microvoids that in turn contain barium sulfate particles. This support provides improved reflectivity particularly at shorter wavelengths.