(fos'fŏr, 'for‵ )

[Fr. phosphore, fr L. phosphorus, morning star, fr Gr. phōsphoros, light-bringer]

A substance that in radiographic intensifying screens, fluoroscopic image intensifiers, or other image receptors converts photons of ionizing radiation into light, thereby amplifying the image.

rare-earth p.An element such as yttrium, gadolinium, or lanthanum, used for ultra-high-speed radiographic intensification screens.